1 - Solvay Institutes

REPORT 2007

REPORT 2007

“Der Solvay Kongress wird stets eine der
schönsten Errinnerungen meines Lebens
bleiben...“
A. Einstein (November 22, 1911),
Nobel Prize in Physics
“To everybody who took part in the meeting
(6th Solvay Conference in Physics) it
was a most instructive and pleasant experience,
and the discussions will surely be
of great help for the future of everyone of
us.“
N. Bohr (November 1, 1930),
Nobel Prize in Physics
“For me it is a great pleasure and a great
honor to chair this 23rd Solvay Conference
in Physics. For all of us who have grown
up in the 20th century, these conferences
have played such an important role in
our collective memory of physics that we
hope that the revived and re-invigorated
Solvay Institutes will continue this tradition
of Solvay Conferences in the same spirit.
Perhaps they will play a role as important
in the 21st century.”
D. Gross (December 1, 2005),
Nobel Prize in Physics

The International Institutes for Physics and Chemistry, founded by
Ernest Solvay, acknowledge with gratitude the generous support of:
the Solvay family
Solvay S.A. - N.V.
the “Université Libre de Bruxelles”
the “Vrije Universiteit Brussel”
the “Loterie Nationale” – “Nationale Loterij”
the “Communauté Française de Belgique”
the “Ministre de la Recherche scientifique de la
Région de Bruxelles Capitale” –
“Minister van Wetenschappelijk Onderzoek
van het Brussels Hoofdstedelijk Gewest”
the “Fondation David et Alice Van Buuren”
the “Fondation Wiener – Anspach”
• the Hotel Metropole
Fondation
Wiener-Anspach

Contents
A word from the Director 10
General Information
o Board of Directors 14
o Scientific Committee for Physics 16
o Scientific Committee for Chemistry 17
o Local Scientific Committee 18
o Honorary Members 19
Solvay Public Events
o Stephen Hawking, Harold Kroto and Solvay Awards 23
o Jean-Marie Lehn 31
International Solvay Chair in Physics: Sir Michael Berry 35
21st Solvay Conference on Chemistry 41
Workshops, Symposia and Schools organized by the Institutes
o Workshop on “Gauge Theories, Strings and Geometry” 55
o Modave Summer School in Mathematical Physics 65
Colloquia 71
Workshops, Conferences and Schools sponsored by the Institutes
o Magnetohydrodynamics Summer Program 85
o Conference on “Computational Physics” 89
o Conference on “Random and Integrable Models in
Mathematics and Physics” 95
o Doctoral School “Quantum Field Theory, Strings
and Gravity” 101
o Experimentarium: Lecture by Michael Berry 105

Seminars and Visitors
o Seminars 110
o Visitors 113
Research on Gravitation, Strings and Cosmology
o Researchers 118
o Research Summary 118
o Research Interests of some Members 121
o Invited Talks at Conferences, Seminars and Schools 129
o List of Publications 132
Research carried out in the group of the Deputy Director
o Members 138
o Research Summary 139
o Invited Talks at Conferences, Seminars and Schools 141
o List of Publications 142
Appendix: Outreach
o Radio Interviews and Edition 146
o Newspapers 147

A word from the Director
A word from the Director
The year 2007 has witnessed
the revival of a
tradition set up by Ernest
Solvay in the early 20th
century.
The founder of the Solvay
Institutes wanted to have
conferences on chemistry
held on a periodic basis
and devoted to challenging
fundamental questions
in chemistry. Due to the occurrence
of the First World
War, the first Solvay Conference on Chemistry
took place only in 1922. Nineteen other
ones followed it. The previous Solvay Conference
on Chemistry was organized in 1995,
twelve years ago. Since then, the cycle had
been interrupted.
It was therefore a challenge to revive the tradition.
This challenge was successfully met this
year with the organization of the 21st Solvay
Conference on Chemistry, “From Noncovalent
Assemblies to Molecular Machines”, during
which the discussions have focused on
the fascinating issues of molecular machines
– so important for biology – and of the chemical
principles on which they are based. In the
name of the Institutes, it is a pleasure to thank
the chair of the Conference, Professor Jean-
Pierre Sauvage, the Solvay Scientific Committee
for Chemistry, the rapporteurs, the session
chairs and all the participants that made
the 21st Solvay Conference an exceptional
scientific success. We now look forward to
the 22nd Solvay Conference on Chemistry,
to be held in 2010.
In the wake of the Conference on Chemistry,
and in keeping with a tradition that was initiated
in 2005, the Institutes organized a public
event open to all on the Sunday following the
conference. The public lecture “De la Matière
à la Vie : la Chimie ? La Chimie !” was delivered
by Nobel Laureate Jean-Marie Lehn who
captivated the audience for more than one
hour and made it marvel at supramolecules,
molecular recognition and the remarkable
potential of this field. He concluded with the
famous words of the mathematician David
Hilbert: “Wir müssen wissen. Wir werden
wissen.“ (“We must know. We shall know.”),
a program that captures very well the mission
of the Solvay Institutes. The public lecture was
followed by a debate on “Chemistry? More
than ever!” during which the public could ask
questions to a panel of distinguished chemists.
It led to very exciting discussions.
It was the same desire to popularize science
among the general public that made the Institutes
co-organize with the Solvay Company
a public event in May of 2007 where
the renowned Cambridge physicist Stephen
Hawking and Nobel Laureate Harold Kroto
gave popular lectures, one on “The Origin of
the Universe” and the other on “Architecture
in Nanospace”. This was again a notable success,
which attracted more than 2000 persons
at the Heysel auditorium. The event was
10

A word from the Director
coupled with the Solvay Award Ceremony,
delivered by the Solvay Company to brilliant
young researchers in physics and chemistry.
The year 2007 was also the second year
of the International Solvay Chair in Physics.
The Solvay Professor was Professor Michael
Berry, from the University of Bristol, who
gave a superb course of lectures on “asymptotic
physics”. Not only physicists from Brussels
attended these but also physicists from
other Belgian universities as well as from the
Netherlands and France. The course was
completed by a public lecture “Seven
Wonders of Physics” that was co-organized
with the ULB museum of physics (“Experimentarium”).
The repeated success of the International
Solvay Chair in Physics has convinced
us to launch in 2008 the International Solvay
Chair in Chemistry.
The International Solvay Institutes have also
organized or sponsored workshops and
conferences on themes ranging from gauge
theories, strings and gravity to computational
physics and random matrices. We have
also supported a summer research program
on magnetohydrodynamics as well as two
graduate schools. Training through research
is indeed one of the goals pursued by the
Institutes. Hundreds of scientists took part in
these activities. Finally, our colloquium series
has now become a well-established and wellattended
tradition.
All these activities are reviewed in the present
report, together with the research carried out
by the scientists affiliated with the Institutes.
On the administrative side, the year 2007 has
also been a year of important changes since
our Board of Directors was renewed, with an
eye to strengthen the visibility of the Institutes
in the civil society. I would like to welcome the
new members who have accepted to help us,
and to thank the leaving members for their assistance
through so many years.
At the same time, it was decided to create an
International Advisory Committee composed
of renowned scientists, whose tasks are to
evaluate periodically our activities, to make
suggestions and to report to the Board of Directors.
The mission of this Committee, which
advises on the daily activities of the Institutes,
is complementary to that of the International
Scientific Committees for Physics and Chemistry,
which are in charge of the Solvay Conferences
on Physics and Chemistry. We are most
grateful to Professor Lars Brink from Chalmers
University for having accepted the important
responsibility of chairing the International
Advisory Committee.
While we keep consolidating and expanding
our scientific activities, we continue at the same
time to improve our financial situation through
strict management practices. The straight
loan has been reduced and represents now
only a fraction of what it was at the end of
2003. This effort will be pursued with the
same willpower. This necessary stabilizing of
our finances would not have been possible
without the firm hand of our treasurer, Professor
Bingen.
Finally, I would also like to thank all the
sponsors of the Solvay Institutes who made
possible the activities developed in 2007.
11

A word from the Director
These are the Université Libre de Bruxelles,
the Vrije Universiteit Brussel, the Solvay Company,
the Belgian National Lottery, the Communauté
Française de Belgique, the Brussels
Capital Region, the David & Alice Van Buren
Foundation, the Wiener-Anspach Foundation,
the Hôtel Métropole and last but not
least, the Solvay family who, since 1911, has
unfailingly supported the Institutes through
cheerful but also difficult times.
The extraordinary dedication of the entire
staff working at the Institutes is also gratefully
acknowledged.
Marc Henneaux
12

A word from the Director
General Information
13

General Information
Director:
Management and Staff
Deputy Director:
Prof. Marc Henneaux (ULB)
Prof. Franklin Lambert (VUB)
Assistants to the Director: Prof. Anne De Wit (ULB)
Prof. Glenn Barnich (ULB)
Prof. Ben Craps (VUB)
Administrative Assistants: Ms Dominique Bogaerts
Ms Fabienne De Neyn
Ms Stéphanie Deprins
Ms Isabelle Juif
Accountant:
Ms Chantal Verrier
Postal address: International Solvay Institutes - Campus Plaine ULB/CP 231- Bd du Triomphe - B-1050 Brussels - Belgium.
Delivery address: IIPC-Solvay - Campus Plaine ULB - Access 2 - Building NO - 5 th Floor - Office N105A - Bd du Triomphe
B-1050 Brussels - Belgium.
Tel: +32 2 650 54 23/55 42 • Fax: +32 2 650 50 28
Website: www.solvayinstitutes.be • Emails: dobogaer@ulb.ac.be / Isabelle.Juif@ulb.ac.be
Board of Directors
Members
Mr Solvay
Professor Franz Bingen
Emeritus - Professor VUB
Professor Rosette S’Jegers
Vice-rector VUB and Professor VUB
President
Vice-President and Treasurer
Secretary
Professor Françoise Thys-Clément
Honorary Rector and Professor ULB
Mr Philippe Busquin
European Deputy and Former European Commissioner
Baron Daniel Janssen
Honorary Chairman of the Board of Directors of Solvay S.A.
14

General Information
Mr Jean-Marie Solvay
Member of the Board of Directors of Solvay S.A.
Mr Eddy Van Gelder
President of the Administrative Board of the VUB
Professor Jean-Louis Vanherweghem
President of the Administrative Board of the ULB
Honorary Members
Professor Irina Veretennicoff
Professor VUB
Baron Jaumotte
Honorary Rector and Honorary President ULB
Honorary Director
Mr Jean-Marie Piret
Attorney General of the Supreme Court of Appeal
and Honorary Principal Private Secretary to the King
Guests
Professor Marc Henneaux
Professor ULB
Professor Franklin Lambert
Professor VUB
Professor Albert Goldbeter
Professor ULB
Professor Alexandre Sevrin
Professor VUB
Director
Deputy Director
Scientific Secretary of the Committee
for Chemistry
Scientific Secretary of the Committee
for Physics
Mr Pascal De Wit
Adviser Solvay S.A.
Professor Niceas Schamp
Secretary of the Royal Flemish Academy for Sciences and Arts
15

General Information
Scientific Committee for Physics
Members are appointed for a 6-year period term, renewable once.
Chair:
Professor David GROSS, Nobel Prize 2004, Kavli
Institute for Theoretical Physics, Santa Barbara, USA
Members:
Professor Fortunato Tito ARECCHI, Università di Firenze
and INOA, Italy (1 July 2004 - 30 June 2010, Second Term)
Professor Jocelyn BELL BURNELL, University of Bath, UK
(1 July 2004 - 30 June 2010, First Term)
Professor Steven CHU, Nobel Prize 1997, Stanford
University, USA (1 January 2008 - 31 December 2013, First Term)
Professor Claude COHEN-TANNOUDJI, Nobel Prize
1997, Ecole Normale Supérieure, Paris, France
(1 July 2004 - 30 June 2010, Second Term)
Professor Ludwig FADDEEV, V.A. Steklov Mathematical
Institute, Saint-Petersburg, Russia
(1 July 2004 - 30 June 2010, Second Term)
Professor Gerard ’t HOOFT, Nobel Prize 1999, Spinoza
Instituut, Utrecht, the Netherlands
(1 July 2004 - 30 June 2010, Second Term)
Professor Giorgio PARISI, Università La Sapienza, Roma,
Italy (1 January 2008 - 31 December 2013, First Term)
Professor Pierre RAMOND, University of Florida, Gainesville,
USA (1 July 2004 - 30 June 2010, First Term)
Professor Klaus VON KLITZING, Nobel Prize 1985,
Max-Planck-Institut, Stuttgart, Germany
(1 July 2004 - 30 June 2010, First Term)
Scientific Secretary:
Professor Alexandre SEVRIN, Vrije Universiteit Brussel,
Belgium
16

General Information
Scientific Committee for Chemistry
Members are appointed for a 6-year period term, renewable once.
Chair:
Members:
Professor Stuart RICE, University of Chicago, USA
Professor Manfred EIGEN, Nobel Prize 1967, Max-
Planck Institut, Göttingen, Germany (1 June 2005 - 31
May 2011, Second Term)
Professor Graham FLEMING, University of Berkeley,
USA (1 June 2005 - 31 May 2011, First Term)
Professor Harold W. KROTO, Nobel Prize 1996, University
of Sussex, Brighton, UK (1 June 2005 - 31 May 2011, First Term)
Professor Jean-Marie LEHN, Nobel Prize 1987, Collège
de France, Paris, France (1 June 2005 - 31 May 2011, Second Term)
Professor Henk N.W. LEKKERKERKER, Utrecht Universiteit,
the Netherlands (1 June 2005 - 31 May 2011, First Term)
Professor Mario J. MOLINA, Nobel Prize 1995,
Massachusetts Institute of Technology, Cambridge, USA
(1 June 2005 - 31 May 2011, Second Term)
Professor K.C. NICOLAOU, University of California, San
Diego, USA (1 June 2005 - 31 May 2011, First Term)
Professor Kurt WÜTHRICH, Nobel Prize 2002, Institut
für Molekularbiologie und Biophysik, Zurich, Switzerland
(1 June 2005 - 31 May 2011, First Term)
Scientific Secretary:
Professor Albert GOLDBETER, Université Libre de
Bruxelles, Belgium
17

General Information
Local Scientific Committee
Chair:
Members:
Professor Marc HENNEAUX (ULB)
Professor Ben CRAPS (VUB)
Professor Anne DE WIT (ULB)
Professor Pierre GASPARD (ULB)
Professor Paul GEERLINGS (VUB)
Professor Albert GOLDBETER (ULB)
Professor Alexandre SEVRIN (VUB)
18

General Information
Honorary members
Professor Anatole ABRAGAM, Collège de France, Paris, France
Professor Robert BROUT, Université Libre de Bruxelles, Belgium
Professor Claudio BUNSTER, Centro de Estudios Cientificos,
Valdivia, Chile
Professor François ENGLERT, Université Libre de
Bruxelles, Belgium
Professor Ludwig FADDEEV, V.A. Steklov Mathematical
Institute, St Petersburg, Russia
Professor Ephraïm KATCHALSKY, Weizmann Institute,
Rehovot, Israel
Professor I.M. KHALATNIKOFF, Landau Institute of
Theoretical Physics, Moscow, Russia
Professor William LIPSCOMB, Nobel Prize 1976, Harvard
University, USA
Professor Victor P. MASLOV, Moscow State University, Russia
Professor Victor A. SADOVNICHY, Moscow State University,
Russia
Professor Roald SAGDEEV, University of Maryland,
College Park, USA
Professor E.C.G. SUDARSHAN, University of Texas,
Austin, USA
Professor Morikazu TODA, Tokyo University of Education,
Japan
Professor Chen Ning YANG, Nobel Prize 1957, Chinese
University Hong Kong & Tsingha University, Beijing, China
19

Stephen Hawking, Harold Kroto & Solvay Awards
SOLVAY PUBLIC EVENTS

Stephen Hawking, Harold Kroto & Solvay Awards
Stephen Hawking,
Harold Kroto
and Solvay Awards
20 May 2007
STEPHEN HAWKING
Lucasian Professor of Mathematics
”The Origin of the Universe”
HAROLD KROTO
1996 Nobel Prize in Chemistry
”Architecture in Nanospace”
During the event, a short Solvay Awards ceremony will take place
Sponsors:
Avec le soutien du Ministre de la Recherche
scientifique de la Région de Bruxelles-Capitale
Met de steun van de Minister van Wetenschappelijk
Onderzoek van het Brussels Hoofdstedelijk Gewest
With the support of the Minister of Scientific
Research of the Brussels Capital Region
Interprétation simultanée
des exposés en français.
Simultaanvertaling is voorzien
naar het Nederlands.
Inscription (obligatoire),
information et programme sur:
Inschrijving (verplicht),
informatie en programma op:
Registration (compulsory),
information and programme on:
www.solvayinstitutes.be/20May2007
The event is co-organized with
23

Solvay Public Events
On May 20, 2007, the International Solvay Institutes co-organized with the Solvay
Company, the Université Libre de Bruxelles and the Vrije Universiteit Brussel, a free
public event at the Heysel, during which the renowned physicist Stephen Hawking
(author of the best-seller “A brief History of Time”) and the Chemistry Nobel Laureate
Harold Kroto both gave a public lecture.
Prince Laurent and Princess Claire of Belgium graced the event with their presence.
The lectures were translated into Dutch and French. Between the two talks, a brief
ceremony during which the Solvay Awards were given to brilliant beginning researchers
in physics and chemistry took place.
Both speakers are well-known for their unique talents for popularizing science.
The success of the event was such (more than 2000 people from all generations) that
it was necessary to also video-retransmit it in the hall next to the lecture room.
Professor Stephen Hawking is a distinguished theoretical
physicist who has contributed revolutionary
ideas to the theory of gravity, where he made
crucial contributions to the understanding of black
holes and the universe. He holds the Lucasian chair
of mathematics at the University of Cambridge,
which was occupied earlier by Newton. The title of
his lecture was “The Origin of the Universe”.
Professor Harold Kroto revolutionized chemistry
through the discovery of new molecules paving the
way to a new carbon chemistry: fullerenes, carbon
nanotubes etc. He received in 1996 the Nobel Prize
in Chemistry for his work. The title of his lecture was
“Architecture in Nanospace”. He is currently devoting
a good fraction of his time to making chemistry
better known in the general public.
24

Stephen Hawking, Harold Kroto & Solvay Awards
We reproduce here the presentation
speech given by Marc Henneaux, Director
of the Institutes.
Your Royal Highnesses,
Excellencies,
Ladies and Gentlemen,
Dear colleagues, dear friends,
It is a great pleasure to welcome all
of you to today’s public event, which
the International Solvay Institutes coorganize
with the Université Libre de
Bruxelles, the Vrije Universiteit Brussel
and the Solvay Company.
On the 9th of June 1921, Einstein delivered
his first public lecture in England.
That was in Manchester and
the lecture was given in German. In
the next day’s issue, the Manchester
Guardian gave reports of people rioting
to get into the lecture hall when
they found out they could not gain
admission.
Who said that science no longer interests
the general public? Five days after
we opened registration for today’s
public event, the Heysel auditorium
was fully packed. The enthusiasm for
understanding the development of science
is as big today as it was in Einstein’s
time.
In order to avoid the riots, and in view
of the many angry email requests and
furious phone calls we received, we
decided, as appeasement measure,
to also broadcast live today’s event
in the hall next door, to allow an additional
2000 people to benefit from
the lectures. I hope we have been
successful!
The International Solvay Institutes is one
of the best known Belgian research
institutions. The pictures of the Solvay
Conferences (“Conseils Solvay” as they
were called in the early days) have
become symbols of excellence and
are known worldwide. The tradition
of these unique conferences, started in
1911, has continued up to this date.
The names of the Nobel laureates Einstein,
Lorentz, Prigogine and more recently
Gross to cite only a few, are associated
with the Solvay successes.
We have further ambitious projects in
the Solvay Institutes’ tradition of excellence:
international chairs, focused
scientific workshops, grants to bright
PhD students and postdoctoral fellows.
Some of these projects are already in
operation while some others, I am confident,
will become reality in the near
future.
Supporting frontier research at the highest
level in physics and chemistry is the
main mission of the Solvay Institutes. But
we are also convinced that it is our responsibility
as scientists to inform society
on the latest scientific discoveries. For
this reason, we committed ourselves in
2005 to periodically organize public
events during which the best researchers
would deliver popular lectures on
their recent work. I can already announce
that the next Solvay public lecture
will be given on December 2nd by
Nobel laureate Jean-Marie Lehn in the
wake of the 21st Solvay Conference
on Chemistry.
25

Solvay Public Events
We are often asked why we, scientists, do scientific research. I believe
that for most of us, it is curiosity and the desire to understand how
“nature works”, to use a somewhat grandiloquent expression. And like
children, we are not satisfied with easy answers to our interrogations.
And we have also kept intact our ability of astonishment and of wonder
in front of new discoveries. Our curiosity-driven urge to understand and
to explore new territories reveals indeed an amazingly unanticipated
form of beauty in the natural laws.
I am convinced that today’s talks, by two of the most brilliant scientists
of our time, will demonstrate that. The lectures cover topics from
the very large - the universe - to the very small - the nanoworld -,
which are equally fascinating.
When we decided to organize today’s lectures, we were
greeted by many skeptics as being completely crazy. Your
massive presence today demonstrates that we were right
to be crazy. There is a quote by a Chilean poet Vicente
Huidobro, which I appreciate very much – so much in fact
that some of you have heard it already many times from me:
“Si yo no hiciera al menos una locura por año, me volvería
loco” – “If I would not make at least one act of craziness
per year, I would become totally mad”. Before introducing
the lecturers, I would like to thank the people and the
organizations that helped us being crazy this afternoon.
First, our two speakers, of course, who accepted our
invitation in spite of a fully booked agenda, and
managed to squeeze in a visit to Brussels between a
zero gravity flight or a trip to New Zealand and many
other exciting invitations. Second, our maecenas, the Solvay
family, who still supports us with the same conviction after 5 generations.
Third, our traditional institutional sponsors, the Solvay Company, the Université Libre
de Bruxelles, the Vrije Universiteit Brussel, the Belgian National Lottery, the Communauté
Française de Belgique, the Van Buuren Foundation and the hotel Metropole.
I also wish to acknowledge a precious grant from the Brussels Capital Region that we
received for this occasion, as well as the Heysel administration for its enormous help.
And last but not least, I would like to thank the infinite dedication of the entire staff
of the Solvay Institutes, who is able, like their director, of being crazy at least once a
year (if not much more!).
°°°°°
26

Stephen Hawking, Harold Kroto & Solvay Awards
Our first speaker this evening is Professor Stephen Hawking. Professor Hawking has
revolutionized our understanding of Einstein’s theory of gravity. He made outstanding
contributions to black hole physics and cosmology. He holds at the University of
Cambridge the Lucasian Chair of Mathematics, held before him by Newton. Stephen
Hawking has exceptional talents for popularizing science. Without further introduction,
I will let him share with us his vision of the universe... let us dream with him!
°°°°°
The interest of the young generations
for science is crucial to the future of our
society. This is why today’s event is free
and open to all. This is also why it is combined
with the Solvay Awards ceremony.
These awards, given by the Solvay company,
recognize the merits of students who
wrote excellent theses in basic or applied
sciences.
It is my great pleasure to give the floor to
Mr. Christian Jourquin, Chairman of the Executive
Committee of the Solvay company,
who will present the awards.
°°°°°
Our second lecturer is Sir Harold Kroto. Who has not heard of “nanoscience”?
The discovery by Professor Kroto of new carbon compounds, Carbon-60 and other
fullerenes, leading to carbon nanotubes, has been a dramatic landmark in that area,
which has completely revolutionized nanoscience. He was awarded the Nobel Prize
in Chemistry in 1996 for this discovery. For a very long time, he has also been
popularizing science and has communicated his passion for it through lectures, presentations
and workshops. Please join me in this other fascinating journey into another
world, the nanoworld.
27

Solvay Public Events
28

Stephen Hawking, Harold Kroto & Solvay Awards
29

Stephen Hawking, Harold Kroto & Solvay Awards
Jean-Marie Lehn
2 December 2007
21st Solvay Conference
on Chemistry
Chemistry?
More than ever!
Talk by Jean-Marie Lehn
1987 Nobel Prize Laureate in Chemistry,
Université Louis Pasteur, Strasbourg, France
«De la Matière à la Vie: la Chimie?
La Chimie!»
Talk followed by a debate
with the participation of
Professors B. Feringa, V. Heitz, J.-P. Launay,
J.-M. Lehn, D. Leigh, A. Moore,
J.-P. Sauvage and F. Stoddart.
Simultaneous interpretation into
French, English and Dutch.
Registration (requested), information and programme
on ”www.solvayinstitutes.be/2dec07.html”
The event is co-organized with
Sponsors:
31

The Solvay Institutes organize on a regular
basis lectures aimed at the general
public and delivered by eminent physicists
or chemists. One of the objectives
of these lectures is to popularize science
and to make it more attractive to the
younger generations.
Solvay Public Events
‘De la Matière à la Vie:
la Chimie? La Chimie!’
The second Solvay public event organized
in 2007 took place as a satellite
meeting to the 21st Solvay Conference
on Chemistry. The eminent
lecturer was the 1987 Nobel
Laureate in Chemistry
Professor Jean-Marie Lehn from the Collège de France and
Strasbourg University. Professor Lehn has made pioneering contributions
to the development and use of molecules that mimic
key biological processes (molecular “recognition”, selective
transport). He is one of the fathers of supramolecular chemistry.
His work has found applications in many areas, going from biomimetism
to nanotechnology and material science.
In this talk entitled “De la Matière à la Vie : la Chimie ?
La Chimie !”, Professor Lehn has embarked the audience in
a fascinating journey across the progresses of Chemistry
throughout the ages and on a thrilling discussion of exciting
new perspectives of research in supramolecular chemistry.
32

Jean-Marie Lehn
A debate took place after the lecture, during which a panel of participants
to the 21st Solvay Conference on Chemistry has answered
questions from the public. After the event, a drink was offered to all
participants and to the public to allow a closer contact between
younger students and the invited scientists.
This event which took place at the Flagey building was a great success
with more than 500 participants.
33

21 st Solvay Conference on Chemistry
INTERNATIONAL SOLVAY
CHAIR IN PHYSICS
1-31 October 2007

International Solvay Chair in Physics
Professor Michael Berry
1–31 October 2007
Bristol University, UK
The International Solvay Institutes were fortunate that Sir Michael Berry, Melville
Wills distinguished Professor of Physics at the University of Bristol, accepted the
2007 International Solvay Chair in Physics.
Since 2006, the International Solvay Chair in Physics has been given every year,
for one to two months, to an eminent physicist who comes to Brussels to give a series
of specialized lectures on a subject of his or her choice, together with an inaugural
lecture aimed at a wider audience.
Professor Michael Berry spent the month of October in Brussels. He gave his inaugural
lecture “Making Light of Mathematics” on October 2. The lecture was attended
by researchers from the ULB, the VUB, as well as other Universities of Belgium and of
neighboring countries. His course of more specialized lectures illustrated the remarkable
diversity and originality of his work and was included in the doctoral training in
physics. Professor Michael Berry also gave on October 23 a public lecture “Seven
Wonders of Physics” in the context of the event entitled “L’Experimentarium fait peau
neuve” organized by the science museum of the ULB (“Experimentarium”).
Professor Sir Michael Berry
Professor Michael Berry is well known for his central
contributions to physics. These are now an integral
part of modern quantum theory. They are used in
areas as diverse as condensed matter physics, field
theory, string theory, gravitational physics, mechanics
and physical chemistry.
His work deals with phenomena in the borderlands
between physical theories - between classical
and quantum, between rays and waves - , which
is the domain of physical asymptotics. He has emphasized
topological and geometrical aspects of
waves and chaos. In particular, he has brought out
the significance of the “geometrical phase” which is
now called “Berry’s phase”.
He received many prestigious distinctions, including
the 1996 Dirac Medal and Prize of the ICTP, and
the 1998 Wolf Prize in Physics. He is a member of
many Academies around the world.
36

International Solvay Chair in Physics
Programme of Chair
Inaugural Lecture
Tuesday 2 October 2007
“Making light of mathematics”
Abstract: “Many ‘mathematical phenomena’ find
application and sometimes spectacular physical illustration
in the physics of light. Concepts such as
fractals, catastrophe theory, knots, infinity, zero, and
even when 1+1 fails to equal 2, are needed to understand
rainbows, twinkling starlight, sparkling
seas, oriental magic mirrors, and simple experiments on interference, polarization
and focusing. The lecture is strongly visual, and nontechnical, though the concepts
are subtle.”
Lectures
Monday 15 October 2007
“Polarization fingerprints in the clear blue sky”
Abstract: “Daylight is polarized, the strength being greatest at points in the sky at right
angles to the sun, and zero at four points: above and below the sun and anti-sun. The
zero-polarization points are ‘fingerprint’ singularities, around which the polarization
direction makes a half-turn. Using elementary singularity theory, the polarization pattern
across the whole sky can be described in a way that fits recent observations
with an accuracy comparable to that of conventional elaborate multiple-scattering
calculations. This recent work is a contribution to a story that started in 1817 and has
been central to our understanding of polarized light.”
“Tsunami asymptotics”
Abstract: “For most of their propagation distance, tsunamis are linear dispersive
waves whose speed is limited by the depth of the ocean and which can be regarded
as a diffraction-decorated caustic in spacetime. For constant depth, uniform as-
37

International Solvay Chair in Physics
ymptotics gives a very accurate compact description of the
tsunami profile generated by an arbitrary initial disturbance.
Variations in depth can focus tsunamis onto cusped caustics,
and this ‘singularity on a singularity’ constitutes an unusual diffraction
problem, whose solution indicates that focusing can
amplify the tsunami energy by an order of magnitude.”
Tuesday 16 October 2007
“Optical vorticulture”
Abstract: “After reviewing the history, beginning in the 1660s,
of lines of phase and polarization singularity in light and other
waves, I will describe our present understanding of their geometry,
and several recent applications: to spiral phase plates (vortex choreography), vortex
knots and links, ubiquity of vortices in interferometers, and quantum cores of the singularities.”
“Physics of nonhermitian degeneracies”
Abstract: “Decoherence makes quantum evolution nonunitary, and such systems, where some
freedoms are ignored, can be described by nonhermitian hamiltonian operators. These differ
most dramatically from hermitian operators in the neighbourhood of degeneracies. Several
examples of nonhermitian degeneracy-dominated physical phenomena will be given, in laser
physics, atom optics, and crystal optics.”
Wednesday 17 October 2007
“Singularity-dominated strong fluctuations”
Abstract: “The fluctuations of a physical quantity can be described by its moments. In many
cases, these diverge as an asymptotic parameter becomes large (or small), through the influence
of geometric singularities. These large moments are described by power laws whose
exponents can be determined from a knowledge of the singularities. Examples are twinkling
starlight, the sex life of moths, certain contour integrals, and several properties of spectra in
quantum chaology.”
38

International Solvay Chair in Physics
“Three recent results on asymptotics of oscillations”
Abstract: “The results are separate, and apparently paradoxical, and have implications
for physics. First, when two exponentials compete, their interference
can be dominated by the contribution with smaller exponent. Second, repeated
differentiation of almost all functions in a wide class generates trigonometric oscillations
(‘almost all functions tend to cosx’). Third, it is possible to find band-limited
functions that oscillate arbitrarily faster than their fastest Fourier component
(‘superoscillations’).”
Thursday 18 October 2007
“Quantum mechanics, chaos, and the music of the primes”
Abstract: “The Riemann hypothesis can be interpreted as stating that the prime numbers contain
‘music’, whose component frequencies are the Riemann zeros. The question «Frequencies
of what?» leads to tantalizing connections with the energy levels of quantum systems
whose corresponding classical motion is chaotic. At the level of statistics, predictions for the
Riemann zeros based on semiclassical quantum asymptotics (with primes as periods of classical
trajectories) have reached a high degree of accuracy and refinement. For the zeros
themselves, the Riemann-Siegel formula and its improvements lead to new ways of calculating
quantum levels.”
Friday 19 October 2007
“Conical diffraction: imaging Hamilton’s diabolical point”
Abstract: “The transformation of a narrow beam into a hollow cone when incident along
the optic axis of a biaxial crystal, predicted by Hamilton in 1832, created a sensation when
observed by Lloyd soon afterwards. It was possibly the first prediction of a qualitatively new
phenomenon using mathematics, the first application of the concept of phase space, and the
prototype of the conical intersections now popular in quantum chemistry. But the fine structure
of the light cone contains many subtle features, slowly revealed by experiment, whose definitive
explanation, involving new mathematical asymptotics, has been achieved only recently,
along with definitive experimental test of the theory. Radically different phenomena, being
intensively studied now, arise when chirality and absorption are incorporated in addition to
biaxiality.”
39

21 st Solvay Conference on Chemistry
21 st SOLVAY CONFERENCE
ON CHEMISTRY
28 November - 1 December
2007
41

21 st Solvay Conference on Chemistry
‘From Noncovalent Assemblies
to Molecular Machines’
Twelve years after the last 1995
Solvay Conference on Chemistry,
the International Solvay
Institutes have proudly revived
this year the tradition of organizing
Solvay Conferences
on Chemistry at the highest
scientific level. The 21st
Solvay Conference on
Chemistry took place
from November 28th to
December 1st, 2007 at
the Hotel Metropole on the theme
“From Noncovalent Assemblies to Molecular
Machines”. This meeting gathered the
leading world experts in one of the most exciting
fields in modern chemistry namely supramolecular
chemistry. The format of the meeting
centered on intense discussions among selected
participants expert in the field has ensured vivid
exchanges of ideas at the frontier of science.
Scientific background
The 21st Solvay Conference on Chemistry has
discussed the fundamental concepts underlying
supramolecular assemblies and their ability of
working as “molecular machines”.
28 November - 1 st December
Molecular machines are very small objects able
to undergo controlled motion or to direct movement
of molecules or ions. They are essential in
numerous biological processes. As an example,
ATP 1 synthase is a natural molecular machine,
functioning as a rotary motor, which uses and
consumes ATP as energy source or, on the contrary,
which is able to fabricate ATP from ADP
and inorganic phosphate. ATP is a universal biological
molecule, associated to all the important
processes related to energy in living systems. This
ATP synthase, one of the most famous biological
motors, produces ATP a bit like the dynamo of a
bicycle wheel produces electricity.
Such intriguing natural molecular motors fascinate
synthetic chemists and motivate them to
invent and create their own synthetic analogs,
either for the challenge that the synthesis of such
systems represents or for the many potential applications
that artificial molecular machines could
give rise to.
Nowadays, the fabrication of artificial molecular
machines, motors, and pumps represents anactive
field of research, the latest developments of
which were discussed at the Solvay Conference.
Such machines have dimensions in the nanometer
range (a nanometer is a million times smaller
than a millimeter). Just as the engine of a car, some
parts of a molecular motor, that are stimulated
by an external signal, are periodically moving
whereas others are motionless. Some chemistry
research groups have made motors that perform
various motions, such as rotation of an axis in a
given direction, extensions or contractions of rodshaped
molecules in a similar way to muscles of
mammals but at the nano scale, gliding of a molecular
fragments along an axis between two
“stations” similarly to a shuttle, to cite a few.
Although molecular machines may appear as relatively
remote from everyday life at first glance,
unprecedented applications are envisaged:
- Molecular electronics would be based on electronic
components reduced to the size of molecules,
i.e. 100 to 1000 times smaller than those
currently used in computer chips.
- Microscopic robots composed of molecular
pieces and tailored to perform specific tasks, such
as local tissue analysis in vein and intestine.
42

21 st Solvay Conference on Chemistry
- Selective transport of ions or molecules through the membranes of living cells.
These molecular machines are the subject of an emerging and very active field of research of modern
chemistry that will contribute to create a safer, cleaner, and better environment for citizens.
1
ATP = Adenosine Triphosphate ; ADP = Adenosine Diphosphate
November 27, 2007 – Le Soir (p.15), Belgium
43

21 st Solvay Conference on Chemistry
Reception at the Brussels City Hall - 27 November 2007
44

21 st Solvay Conference on Chemistry
45

21 st Solvay Conference on Chemistry
Scientific Programme
Wednesday 28 November 2007
9:00 - 9:10 Opening by M. Henneaux (Director of the Solvay
Institutes, Belgium) and J.-P. Sauvage
(Université Louis Pasteur, Strasbourg, France)
Morning session
Chair:
Rapporteur:
“Noncovalent Assemblies: Design and Synthesis”
J. Rebek (Skaggs Institute for Chemical Biology, USA)
M. Fujita (Tokyo University, Japan)
9:10 - 12:00 Talk and Discussion
Afternoon session
Chair:
Rapporteur:
“Template Synthesis of Catenanes and
Rotaxanes”
F. Vögtle (Universität Bonn, Germany)
F. Stoddart (University of California,
Los Angeles, USA)
2:00 - 5:00 Talk and Discussion
Thursday 29 November 2007
Morning session
Chair:
Rapporteur:
“Molecular Machines based on Catenanes
and Rotaxanes”
D.A. Leigh (Edinburgh University, UK)
V. Balzani (Università di Bologna, Italy)
9:00 - 12:00 Talk and Discussion
Afternoon free
46

21 st Solvay Conference on Chemistry
Scientific Programme
Friday 30 November 2007
Morning session
Chair:
Rapporteur:
“Molecular Machines based on
Non-Interlocking Molecules”
T. Aida (Tokyo University, Japan)
B.L. Feringa (Rijksuniversiteit, Groningen,
the Netherlands)
9:00 - 12:00 Talk and Discussion
Afternoon session
Chair:
Rapporteur:
“Towards Molecular Logics and Artificial
Photosynthesis”
A.P. de Silva (Queen’s University, UK)
D. Gust (Arizona State University, USA)
2:00 - 5:00 Talk and Discussion
Saturday 1 December 2007
Morning session
Chair:
Rapporteur:
“From Single Molecules to Practical Devices”
E. Dalcanale (Università di Parma, Italy)
J.-P. Launay (CEMES-CNRS, France)
9:00 - 12:00 Talk and Discussion
47

21 st Solvay Conference on Chemistry
Participants
Last Name First Name Institution
Aida Takuzo University of Tokyo, Japan
Anderson Harry University of Oxford, UK
Astumian R. Dean University of Maine, Orono, USA
Balzani Vincenzo Università di Bologna, Italy
Beer Paul University of Oxford, UK
Brouwer Albert M. Vrije Universiteit Amsterdam, the Netherlands
Credi Alberto Università di Bologna, Italy
Dalcanale Enrico Univeristà di Parma, Italy
de Silva A. Prasanna Queen’s University, Belfast, UK
Fabbrizzi Luigi Università di Pavia, Italy
Feringa Ben L. Rijksuniversiteit Groningen, the Netherlands
Fleming Graham University of California, Berkeley, USA
Fujita Makoto University of Tokyo, Japan
Gust Devens Arizona State University, Tempe, USA
Harada Akira Osaka University, Japan
Heitz Valérie Université Louis Pasteur, Strasbourg, France
Hunter Christopher University of Sheffield, UK
Joachim Christian CEMES-CNRS, Toulouse, France
Kim Kimoon Pohang University of Sciences and Technology, Korea
Launay Jean-Pierre CEMES-CNRS, Toulouse, France
Lehn Jean-Marie Université Louis Pasteur, Strasbourg, France
Leigh David A. University of Edinburgh, UK
Lekkerkerker Henk Universiteit Utrecht, the Netherlands
Michl Josef University of Colorado, Boulder, USA
Moore Ana L. Arizona University, Tempe, USA
Moore Thomas A. Arizona University, Tempe, USA
Nolte Roeland Universiteit Nijmegen, the Netherlands
Otero Toribio F. Universidad Politécnica de Cartagena, Spain
Prost Jacques Ecole Supérieure de Physique et de Chimie
Industrielles, Paris, France
Raymond Kenneth University of California, Berkeley, USA
Rebek Julius The Skaggs Institute for Chemical Biology, La Jolla, USA
Reinhoudt David N. Universiteit Twente, Enschede, the Netherlands
Rice Stuart University of Chicago, USA
48

21 st Solvay Conference on Chemistry
Last Name First Name Institution
Saalfrank Rolf W. Universität Erlangen-
Nürnberg, Germany
Sanders Jeremy Cambridge Center for Molecular
Recognition, UK
Sauvage Jean-Pierre Université Louis Pasteur,
Strasbourg, France
Shanzer Abraham Weizmann Institute of
Sciences, Rehovot, Israel
Shinkai Seiji Kyushu University, Fukuoka,Japan
Shionoya Mitsuhiko University of Tokyo, Japan
Stoddart J. Fraser University of California,
Los Angeles, USA
Vögtle Fritz Universität Bonn, Germany
Wozniak Krzysztof Warsaw University, Poland
49

21 st Solvay Conference on Chemistry
Auditeurs
Last Name First Name Institution
Bartik Kristin ULB, Brussels, Belgium
Bonifazi Davide FUNDP, Namur, Belgium
De Feyter Steven K.U.Leuven, Belgium
Durot Stéphanie Université Louis Pasteur, Strasbourg, France
Gaspard Pierre ULB, Brussels, Belgium
Geerlings Paul VUB, Brussels, Belgium
Geerts Yves ULB, Brussels, Belgium
Goldbeter Albert ULB, Brussels, Belgium
Hofkens Johan K.U.Leuven, Belgium
Jabin Ivan ULB, Brussels, Belgium
Jonas Alain UCL, Louvain-la-Neuve, Belgium
Kirsch Fanny ULB, Brussels, Belgium
Lefever René ULB, Brussels, Belgium
Mandel Paul ULB, Brussels, Belgium
Martins Jose Universiteit Gent, Belgium
Moucheron Cécile ULB, Brussels, Belgium
Reisse Jacques ULB, Brussels, Belgium
Sergeyev Sergey ULB, Brussels, Belgium
Vincent Stéphane FUNDP, Namur, Belgium
50

21 st Solvay Conference on Chemistry
Reception at the ”Maison Ernest Solvay”
29 November 2007
51

Gauge Theories, Strings & Geometry
WORKSHOPS, SYMPOSIA
AND SCHOOLS ORGANIZED
BY THE INSTITUTES
53

Gauge Theories, Strings & Geometry
Workshop on ‘Gauge Theories
Strings and Geometry’
9-11 May 2007
55

Workshops & Schools organized by the Institutes
The aim of the Workshop was to gather top
level researchers working on the relations between
gauge theories and string theory.
There were 20 seminars by invited speakers,
and an overall attendance of almost 100
participants (speakers included), many of
them from abroad, which is a testimony to the
interest in the field of research and the Workshop
itself. The main idea addressed by the
workshop is that string theory incorporates
the physics of gauge theories, but sometimes
in a way which is reminiscent of holography.
This powerful “duality” allows in particular
cases to describe through string theory some
strongly coupled gauge theory phenomena,
and vice-versa.
Some specific topics discussed during the
Workshop were the following:
° Dynamical (super)symmetry breaking
° Metastable vacua in gauge and string
theories
Scientific Committee
Riccardo Argurio (ULB, Brussels, Belgium)
Paolo Di Vecchia (Nordita, Stockholm,
Sweden),
Nick Dorey (University of Cambridge, UK)
Frank Ferrari (ULB, Brussels, Belgium)
Igor Klebanov (Princeton University, USA)
Juan Maldacena (Institute of Advanced Studies,
Princeton, USA)
Nathan Seiberg (Institute of Advanced Studies,
Princeton, USA)
Alberto Zaffaroni (Università di Milano-Bicocca,
Italy)
Organising Committee
Riccardo Argurio (ULB, Brussels, Belgium)
Ben Craps (VUB, Brussels, Belgium)
Frank Ferrari (ULB, Brussels, Belgium)
Alexander Sevrin (VUB, Brussels, Belgium)
° Non - critical string backgrounds and
holographic QCD
° Gauge theories and QCD from
intersecting branes
° Flavor physics and chiral symmetry from
string theory
° Integrability and AdS/CFT
° BPS states counting
56

Gauge Theories, Strings & Geometry
List of Invited Speakers
Niklas Beisert (Max-Planck Institut, Potsdam,
Germany)
Nick Dorey (University of Cambridge, UK)
Gabriele Ferretti (Chalmers/Göteborgs Universitet,
Sweden)
Rajesh Gopakumar (Harish-Chandra Research
Institute, Allahabad, India)
Amihay Hanany (Perimeter Institute, Waterloo,
Canada)
Tim Hollowood (Swansea University, UK)
David Kosower (CEA-Saclay, Gif-sur-Yvette,
France)
David Kutasov (University of Chicago, USA)
Shiraz Minwalla (Tata Institute of Fundamental
Research, Mumbai, India)
Carlos Nunez (University of Wales
Swansea, UK)
Angel Paredes (Ecole Polytechnique, Palaiseau,
France)
Alexander Polyakov (Princeton University, USA)
Shigeki Sugimoto (Nagoya University, Japan)
Andrei Starinets (Perimeter Institute, Waterloo,
Canada)
Matthias Staudacher (Max-Planck Institut, Potsdam,
Germany)
Jan Troost (Ecole Normale Supérieure, Paris,
France)
Angel Uranga (CERN, Switzerland)
Alberto Zaffaroni (Università di
Milano-Bicocca, Italy)
57

Workshops & Schools organized by the Institutes
8:30 - 9:00 Registration
Wednesday 9 May 2007
9:00 - 9:15 Opening by M. Henneaux
9:15 - 10:00 D. Kutasov (University of Chicago, USA)
“Dynamical symmetry breaking from intersecting branes”
10:00 - 10:45 A. Uranga (CERN, Switzerland)
“Metastable vacua in runaway quiver gauge theories”
10:45 - 11:15 Coffee Break
11:15 - 12:00 R. Gopakumar (Harish-Chandra Research Institute, India)
“Comments on the worldsheet description of free large
N gauge theories”
12:00 - 12:45 J. Troost (Ecole Normale Supérieure, France)
“D-branes in non-critical superstrings and duality in super
symmetric gauge theories”
12:45 - 15:00 Lunch
Programme
15:00 - 15:45 A. Polyakov (Princeton University, USA)
“Causality vs Stability of the de Sitter spaces”
15:45 - 16:15 Coffee Break
16:15 - 17:00 N. Dorey (University of Cambridge, UK)
“Singularities of the Magnon S-matrix”
17:00 - 17:45 A. Paredes (Ecole Polytechnique, France)
“Chiral symmetry breaking as tachyon condensation”
58

Gauge Theories, Strings & Geometry
Thursday 10 May 2007
9:00 - 9:45 T. Hollowood (Swansea University, UK)
”The Refractive Index of Curved Space: the Fate of
Causality in QED”
9:45 - 10:30 D. Kosower (CEA-Saclay, France)
”A Maximally Supersymmetric Journey from Weak to
Strong Coupling”
10:30 - 11:00 Coffee Break
11:00 - 11:45 A. Starinets (Perimeter Institute, Canada)
”Transport properties of strongly coupled plasmas and
gauge/gravity duality”
11:45 - 12:30 A. Hanany (Perimeter Institute, Canada)
”Counting BPS operators - the Plethystic Story”
12:30 - 14:15 Lunch
14:15 - 15:00 A. Zaffaroni (Università di Milano-Bicocca, Italy)
”Chiral Rings and Generating Functions for Superconformal
Gauge Theories”
19:30 Banquet at Hotel Metropole
59

Workshops & Schools organized by the Institutes
Friday 11 May 2007
9:00 - 9:45 G. Ferretti (Chalmers/Göteborgs Universitet, Sweden)
”Exotic Instantons at Orbifold Singularities”
9:45 - 10:30 N. Beisert (Max-Planck Institut, Germany)
”Integrability in AdS/CFT”
10:30 - 11:00 Coffee Break
11:00 - 11:45 C. Nunez (University of Wales Swansea, UK)
”String Theory and Flavor Physics”
11:45 - 12:30 S. Sugimoto (Nagoya University, Japan)
”Baryons from instantons in holographic QCD”
12:30 - 15:00 Lunch
15:00 - 15:45 M. Staudacher (Max-Planck Institut, Germany)
”Dressing, Nesting and Wrapping in AdS/CFT”
15:45 - 16:15 Coffee Break
16:15 - 17:00 S. Minwalla (Tata Institute of Fundamental Research, India)
”Plasmarings in Large N gauge Theories”
17:00 - 17:30 A. Polyakov (Princeton University, USA)
Closing remarks
60

Gauge Theories, Strings & Geometry
Participants
Last Name First Name Institution
Abou Zeid Mohab Vrije Universiteit Brussel, Belgium
Anabalon Andres CECS, Valdivia and Concepcion University, Chile
Andriot David Université Pierre et Marie Curie Paris VI, France
Barnich Glenn Université Libre de Bruxelles, Belgium
Basso Benjamin Université PARIS XI, France
Berman David Queen Mary College, University of London, UK
Bigazzi Francesco Université Libre de Bruxelles, Belgium
Bolognesi Stefano Niels Bohr Institute, Copenhagen, Denmark
Bonelli Giulio SISSA/ISAS, Trieste, Italy
Bouatta Nazim Université Libre de Bruxelles, Belgium
Bouwknegt Peter Australian National University, Canberra,
Australia
Calmet Xavier Université Libre de Bruxelles, Belgium
Chesterman Michael CEA Saclay, France
Closset Cyril Université Libre de Bruxelles, Belgium
Compère Geoffrey Université Libre de Bruxelles, Belgium
De Roo Frederik Universiteit Gent, Belgium
De Rydt Jan K.U.Leuven, Belgium
Detournay Stéphane Università di Milano, Italy
Drummond James LAPTH, Annecy, France
Dudal David Universiteit Gent, Belgium
Evnin Oleg Université Libre de Bruxelles, Belgium
Evslin Jarah Université Libre de Bruxelles, Belgium
Forcella Davide SISSA, Bergamo, Italy
Forte Luca Antonio Université Libre de Bruxelles, Belgium
Francia Dario Università di Roma, Italy
Gabriel Catren Ecole Polytechnique de Paris, France
Giribet Gaston Universidad de Buenos Aires, Argentina
Goncharenko Igor Peoples’ Friendship University of Russia,
Moscow, Russia
Henneaux Marc Université Libre de Bruxelles, Belgium
Hertog Thomas Université de Paris VII, France
Houart Laurent Université Libre de Bruxelles, Belgium
Imeroni Emiliano Swansea University, UK
61

Workshops & Schools organized by the Institutes
Participants
Last Name First Name Institution
Jamsin Ella Université Libre de Bruxelles, Belgium
Janssen Bert Universidad de Granada, Spain
Keurentjes Arjan Vrije Universiteit Brussel, Belgium
Klose Thomas Uppsala Universitet, Sweden
Koerber Paul Max-Planck-Institut für Physik, Munich, Germany
Koshelev Alexey University of Crete, Heraklion, Greece
Krishnan Chethan Université Libre de Bruxelles, Belgium
Kuperstein Stanislav Université Libre de Bruxelles, Belgium
Liuba Mazzanti Ecole Polytechnique, Palaiseau, France/Università di
Milano, Italy
Lopez Alicia King’s College, University of London, UK
Maccaferri Carlo Vrije Universiteit Brussel, Belgium
Mariotti Alberto Università di Milano Bicocca, Italy
Marmorini Giacomo Scuola Normale Superiore, Pisa, Italy
Martucci Luca K.U.Leuven, Belgium
Nitti Francesco Ecole Polytechnique, Palaiseau, France
Njie Saihou Kombo Technology and Business Institute, Banjul, Gambia
Onyemaechi Daniel Ofili Kombo Technology and Business Institute, Banjul, Gambia
Orani Stefano Université Libre de Bruxelles, Belgium
Persson Daniel Université Libre de Bruxelles, Belgium
Rafik Aouane Université Es-Senia, Oran, Algeria
Ruuge Artur Universiteit Antwerpen, Belgium
Smyth Paul K.U.Leuven, Belgium
Spindel Philippe Université Mons-Hainaut, Belgium
Tabti Nassiba Université Libre de Bruxelles, Belgium
Tamassia Laura K.U.Leuven, Belgium
Taylor Marika Universiteit van Amsterdam, the Netherlands
Teerlinck Dirk Universiteit Gent, Belgium
Terryn Dimitri Vrije Universiteit Brussel, Belgium
Troost Jan Ecole Normale Superieure, Paris, France
Tytgat Michel Université Libre de Bruxelles, Belgium
Van den Bleeken Dieter K.U.Leuven, Belgium
Van Doorsselaere Jos Universiteit Gent, Belgium
Van Herck Walter K.U.Leuven, Belgium
Vercauteren David Universiteit Gent, Belgium
Verschelde Henri Universiteit Gent, Belgium
62

Gauge Theories, Strings & Geometry
Participants
Last Name First Name Institution
Vinci Walter Università di Pisa, Italy
Wallet J-Christophe Université PARIS XI, France
Wens Vincent Université Libre de Bruxelles, Belgium
Wijns Alexander Vrije Universiteit Brussel, Belgium
Wyder Thomas K.U.Leuven, Belgium
Yee Jung-Tay University of Helsinki, Finland
63

Gauge Theories, Strings & Geometry
Modave Summer School in
Mathematical Physics
29 August - 4 September 2007
65

Workshops & Schools organized by the Institutes
The third edition of the Modave Summer School in Mathematical Physics
was organized from the 29th of August to the 4th of September 2007, by
young PhD students and Post-docs of the Service de Physique Théorique
et Mathématique of the ULB, the Theoretical Particle Physics Group of the
VUB, the Service de Physique des Particules of the Université de Mons-Hainaut,
the String Theory Group of Universitá degli Studi di Milano I and the
I.H.E.S.
The aim was to study tools useful for research in theoretical physics of fundamental
interactions, generally supposed to be known but too seldom
explained in details. The summer school consisted of about 6 hours of
lectures a day, during the morning and in the late afternoon. Participants
were given the opportunity to give a short presentation on their work
(10-15 min). The atmosphere was informal and relaxed, so as
to encourage the participants to interact with the speakers,
who are also young researchers. Reference books were also
placed at the disposal of everyone. The major part of the afternoon
was left free, in order to allow spontaneous discussions
and/or meetings for questions and answers in connection with
the morning’s courses. Pastoral walks, cultural visits were also
possible in the afternoon.
Organising Committee
N. Bouatta
G. Compère
S. de Buyl
S. Detournay
V. Mathieu
N. Tabti
V. Wens
A. Wijns
66

Modave Summer School
Programme
Lectures
Integrable models
(C. Sieg, 3h)
Algebraic topology
(J. Evslin, A. Wijns, 4h)
Kac-Moody algebras
(D. Persson, N. Tabti, 4h)
Poisson and symplectic geometry
(S. de Buyl, S. Detournay, 4h)
Background field method and pinch technique
(V. Mathieu, 3h)
D-branes, sheaves and categories
(C. Krishnan, 3h)
Topological strings
(A. Collinucci, T. Wyder, 4h)
Modular forms
(D. Van den Bleeken, 3h)
Special geometry
(J. Rosseel, 2h)
67

Gauge Theories, Strings & Geometry
A word from the Director
68

Modave Summer School
Participants
Nazim Bouatta (ULB,
Brussels, Belgium)
Andrea Brini (SISSA,
Trieste, Italy)
Cyril Closset (ULB,
Brussels, Belgium)
Andres Collinucci
(K.U.Leuven, Belgium)
Geoffrey Compère (ULB,
Brussels, Belgium)
Sophie de Buyl (IHES,
Bures-sur-Yvette, France)
Frederik De Roo (VUB,
Brussels, Belgium)
Jan De Rydt
(K.U.Leuven, Belgium)
Térence Delsate
(UMH, Mons, Belgium)
Stéphane Detournay
(University of Milano I,
Italy)
Jarah Evslin
(ULB, Brussels, Belgium)
Abdelmoubine Amar Henni
(SISSA, Trieste, Italy)
Ella Jamsin
(ULB, Brussels, Belgium)
Euihun Joung
(Paris7, France)
Chethan Krishnan
(ULB, Brussels, Belgium)
Stanislav Kuperstein
(ULB, Brussels, Belgium)
Carlo Maccaferri
(ULB, Brussels, Belgium)
Vincent Mathieu
(UMH, Mons, Belgium)
Daniel Persson (ULB,
Brussels, Belgium)
Jan Rosseel
(K.U.Leuven, Belgium)
Mitul Shah
(University of Oxford, UK)
Christoph Sieg
(Universitá degli Studi
di Milano, Italy)
Nassiba Tabti
(ULB, Brussels, Belgium)
Dimitri Terryn
(VUB, Brussels, Belgium)
Dieter Van den Bleeken
(K.U.Leuven, Belgium)
Walter Van Herck
(K.U.Leuven, Belgium)
Bert Vercnocke
(K.U.Leuven, Belgium)
Vincent Wens
(ULB, Brussels, Belgium)
Alexander Wijns
(VUB, Brussels, Belgium)
Thomas Wyder
(K.U.Leuven, Belgium)
69

Gauge Theories, Strings & Geometry
COLLOQUIA
71

Colloquia
Inflation: Confronting Predictions
with Observations
Professor Viatcheslav MUKHANOV
Ludwig - Maximilians - Universität München, Germany
6 February 2007
Abstract
“I will discuss the robust, scenario-independent predictions of cosmic inflation and
compare them with the results of the current observations of the CMB fluctuations.”
72

Colloquia
From Chemical Topology to
Molecular Machines and Motors
Professor Jean–Pierre SAUVAGE
Université Louis Pasteur/CNRS
Strasbourg, France
27 February 2007
Abstract
“Catenanes (interlocking rings) and knots represent
attractive synthetic challenges for molecular chemists.
Besides their topological properties, these
systems can be regarded as works of art at the
nanometre scale. The creation of such complex
molecules also demonstrates that synthetic chemistry
is now powerful enough to tackle problems whose
complexity is sometimes reminiscent of biology,
although the elaboration of molecular ensembles
displaying properties as complex as biological assemblies
is still a long-term challenge.
The field of artificial molecular machines and motors
has experienced a spectacular development
in the course of the last decade, in relation with
biological motors (as mimics) or information storage
and processing at the molecular level (toward
molecule-based computers). These systems
are multicomponent assemblies undergoing largeamplitude
geometrical changes or leading to the
locomotion of one of the components, under the
action of an external stimulus.
A recent example consists of a rotaxane whose motions
can be triggered by using anelectrochemical
signal: the oxidized form (copper(II)) corresponds
to a 5-coordinate situation
whereas the reduced state
(copper(I)) is 4-coordinate.
For this electrochemically
driven machine, pirouetting
of the ring occurs on the millisecond
time scale. Another
particularly significant example
is that of a rod-shaped
molecule which can be contracted
or stretched at will
under the action of a chemical
signal. It can thus be regarded
as a «nano-muscle»,
its size varying between 6.5
and 8.5 nm.
Recently, our group has also proposed a transition
metal-based strategy for making two-dimensional
interlocking and threaded networks. Large
cyclic assemblies containing several copper(I) centres
could be prepared which open the gate to
controlled dynamic two-dimensional systems and
membrane-like structures consisting of multiple catenanes
and rotaxanes.
In the course of the last three years, we have been
much interested in endocyclic or exotopic but non
sterically hindering chelates. These compounds
are based on carefully designed 3,3’-bi-isoquinoline
derivatives. Some of them have even been
incorporated into macrocyclic compounds. A particularly
efficient and fast moving molecular «shuttle»
based on such a chelate has been made and
investigated as well as three-component molecular
entanglements constructed by assembling three
such ligands around an octahedral metal centre.
Although it is still premature to claim that this new
field will become practically important in a shortterm
prospective, we think it is a very active and
conceptually important field of research.”
73

Colloquia
Do we understand
Crystal Nucleation?
Professor Daan FRENKEL
Vrije Universiteit Amsterdam, the Netherlands
20 March 2007
Abstract
“Crystal nucleation is a very common phenomenon, but it is not well understood. For
almost a century, the theoretical models that predict rate of crystal nucleation could
not be tested in detail. That situation is now changing because of two developments
in colloidal science: 1. better realspace probes of (colloidal) crystal nucleation and 2.
better numerical modeling techniques. In my talk, I will review recent advances in our
understanding of homogeneous and heterogeneous crystal nucleation and I will indicate
some of the areas where our understanding is still far from complete. Examples
will include: colloidal crystals, molten salts and extraterrestrial diamonds.”
74

Colloquia
Single Molecule Spectroscopy
and its Applications
Professor Johan HOFKENS
Katholieke Universiteit Leuven, Belgium
24 April 2007
Abstract
“Over the last 15 years, single molecule spectroscopy (SMS) has been established as a new tool
in the ever expanding range of spectroscopic methods. SMS is especially useful to study inhomogeneous
systems. Biological systems are by their nature highly heterogeneous and as such perfect
targets for SMS. From this it is clear that, next to biological samples, polymers form a study object
of SMS as polymers are very often heterogeneous in their behavior. Many theories that describe
polymer properties are based on a microscopic picture that now can be evaluated experimentally
by applying single molecule techniques. Furthermore, single molecule techniques are very useful
for the study of dynamic processes since no synchronization is needed when dynamic events are
studied. In this contribution, we will show how different single molecule techniques can be used in
the study of dynamic processes at the molecular level.”
75

Strings, Gauge Theory and
Integrability: What Old Ideas
from Condensed Matter are Teaching
us about Fundamental Physics
Professor Curtis CALLAN
Colloquia
Princeton University, USA
8 May 2007
Abstract
“String theory has redefined itself several times since its invention forty years ago. A
recent chapter in this saga is the proposal that string theory in ten dimensions is dual
to a supersymmetric gauge theory in four dimensions. In its weak form, duality implies
that the strong coupling behavior of the gauge theory should be identical to that of a
weakly-coupled gravity theory (in a different dimension), a surprising assertion which
has received numerous qualitative checks. In its strong form, duality says that the two
theories should be identical, something which, in the absence of exact solutions for
either theory, is hard to verify. In a dramatic recent development, duality has been
traced to the presence, in both theories, of an underlying integrable one-dimensional
spin chain, of a type familiar from condensed matter physics. Integrability allows exact
solutions to be constructed, (using techniques invented by Bethe in the 1930’s!) and
this has opened up the possibility of directly verifying the strong form of duality. The
first results of exploiting these new ideas are most impressive and my goal in this talk
is to convey to a general physics audience some idea of what has been achieved.
While I will have to gloss over technical details, I hope to be able to communicate
a clear sense of why these new developments are of great conceptual, and maybe
even practical, importance.”
76

Colloquia
Making Light of Mathematics
Professor Michael BERRY
Bristol University, UK
2 October 2007
Abstract
“Many ‘mathematical phenomena’ find application and sometimes spectacular physical illustration
in the physics of light. Concepts such as fractals, catastrophe theory, knots, infinity, zero, and even
when 1+1 fails to equal 2, are needed to understand rainbows, twinkling starlight, sparkling seas,
oriental magic mirrors, and simple experiments on interference, polarization and focusing. The
lecture is strongly visual, and nontechnical, though the concepts are subtle.”
77

Colloquia
Gravitational Wave Searches:
Progress Report
Professor Bernard SCHUTZ
Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik,
Potsdam, Germany & LIGO Scientific Collaboration
30 October 2007
Abstract
“The giant gravitational wave interferometers of the LIGO and GEO projects have just
completed a two-year long observational run with «first-stage» sensitivity. While the
data are still be analysed, some interesting upper limits have already been announced
on specific gamma-ray bursts and pulsars. After the current hardware upgrade, LIGO
and VIRGO will resume in 2009, with much better chances of detections, and by
2013 the final upgrade will make detections virtually certain. Meanwhile ESA and
NASA continue to develop LISA for launch in 2018, starting with the launch of LISA
Pathfinder in 2010. I will survey current developments on all these fronts.”
78

Colloquia
Physiological Relevance of
Molecular Motors
Professor Jacques PROST
ESPCI and Institut Curie, Paris, France
27 November 2007
Abstract
“Much of the cell mechanics, morphology and motility is determined by the dynamical properties
of an actin network moving under the action of molecular motors and by a continuous process of
polymerization/depolymerization called treadmilling. The actin network constitutes a physical gel
the cross-links of which are both temporary and mobile. It is more complex than a physical gel in
that it has a macroscopic polarity due to the microscopic polarity of actin filaments and in that the
cross-links are dynamically redistributed by molecular motors. This requires an energy input, which
implies that this system is intrinsically out of equilibrium. I will show how one can write down a set
of phenomenological equations, which can describe this situation. I will illustrate the usefulness of
this approach by considering lamellipodium motion and cell oscillatory instabilities, mitosis and
synapse formation.”
79

Colloquia
Reconsidering the 1927 Solvay
Conference
Professor Antony VALENTINI
Centre de Physique Théorique, Marseille, France
18 December 2007
Abstract
“We reconsider the crucial 1927 Solvay conference in the context of current research
in the foundations of quantum theory. Contrary to folklore, the interpretation
question was not settled at this conference and no consensus was reached; instead,
a range of sharply conflicting views were presented and extensively discussed.
Today, there is no longer an established or dominant interpretation of quantum theory,
so it is important to re-evaluate the historical sources and keep the interpretation debate
open. The proceedings of the conference contain much unexpected material.
After providing a general overview, we shall focus (a) on the extensive discussions of
de Broglie’s pilot-wave theory, which de Broglie presented for a many-body system,
including the much misunderstood critique by Pauli, and (b) on Born and Heisenberg’s
presentation of a ‘quantum mechanics’ apparently lacking in wave function collapse
or fundamental time evolution. This talk is based on our English translation and commentary
of the proceedings of the conference, ‘Quantum Theory at the Crossroads’
(forthcoming with Cambridge University Press, ISBN: 9780521814218).”
80

Colloquia
81

Sponsored by the Institutes
WORKSHOPS,CONFERENCES
AND SCHOOLS SPONSORED
BY THE INSTITUTES
83

Sponsored by the Institutes
Magnetohydrodynamics
Summer Program
15-27 July 2007
85

Conferences & Schools sponsored by the Institutes
MHD Summer Program 2007
15-27 July 2007
The 2nd “MHD summer program” in Brussels took place between the 15th of July and the
27th of July 2007 (2 weeks) and gathered about 50 scientists.
The research program focused on magnetohydrodynamics (MHD), the science that describes
the coupling between fluid mechanics and electromagnetism. Research in MHD is intrinsically
interdisciplinary. It is relevant to fields as diverse as astrophysics, metallurgy, crystal growth
or nuclear fusion. The originality of the organisation is that the participants spent their time in
Brussels working on research projects and on scientific exchanges rather than attending talks
and seminars.
As for the first edition of the event, the organizing committee consisted of Prof Daniele Carati
(ULB, Belgium), Prof Bernard Knaepen (ULB, Belgium) and Prof Stavros Kassinos (University
of Cyprus, Cyprus), with the help of Fabienne De Neyn, Stéphanie Deprins and Isabelle Juif.
The scientific committee included: Prof Sergei Molokov (Coventry, UK), Prof René Moreau
(Grenoble, France) and Prof Andre Thess (Ilmenay, Germany).
The event again proved a unique opportunity for ULB scientists (academic staff, post-docs
and PhD students) to interact extensively with specialists coming from all over the world.
The organizers are very grateful to the following sponsors without which the summer program
could not have been held:
° EURATOM-Belgian state Association
° Action de Recherche Concertée de la Communauté Française de Belgique
(Contract N.02/07-283)
° Fonds de la Recherche Fondamentale Collective (Contract N. 2.4542.05)
° International Solvay Institutes for Physics and Chemistry
° COST action P17
° European Science Foundation, EURYI programme
° Interuniversity Attraction Pole P6/08 Physical chemistry of plasma - surface
interactions
86

MHD Summer Program 2007
This year’s invited participants along with their research projects included:
Participants and projects
Thomas Boeck and Dmitry Krasnov (Technische Universität Ilmenau)
Project: Large eddy simulation of turbulent Hartmann flow
Leo Bühler (Forschungszentrum Karlsruhe)
Project: Unstable side layers in rectangular duct flow
Arakel Petrosyan and Aleksandr Chernyshov (Space Research Institute of the Russian Academy
of Science)
Project: Large eddy simulation of compressible MHD turbulence
Alban Pothérat and Vitali Dymkou (Technische Universität Ilmenau)
Project: Numerical and theoretical study of the transition between two-dimensional and
three-dimensional magnetohydrodynamic turbulence under imposed magnetic field
Harikrishnan Radhakrishnan (University of Cyprus)
Project: Large Eddy Simulations of MHD flows with conducting walls
Jacques Léorat, Caroline Nore and Adolfo Ribeiro (Observatoire de Paris-Meudon, LIMSI-
CNRS)
Project: A new hybrid Spectral-Finite Element Method for MHD problems
Owen Matthews (Paul Scherrer Institute)
Project: Large Eddy Simulation of Accretion Discs
Frank Plunian and Rodion Stepanov (LGIT, Grenoble / Institute of Continuous Media Mechanics,
Perm)
Project: A new shell model for anisotropic MHD turbulence
Daniel Price (University of Exeter)
Project: Smooth Particle Hydrodynamics (SPH) for MHD
Damian Rouson and Xiaofeng Xu (U.S. Naval Research Laboratory, Mindware Engineering)
Project: Variational multiscale LES of quasi-static MHD turbulence with linear forcing
87

Conferences & Schools sponsored by the Institutes
Participants and projects
Philipp Schlatter (Royal Institute of Technology, Stockholm)
Project: Passive scalar transport in transitional and turbulent Hartmann flows with Spectral Methods
Oleg Zikanov and Anatoliy Vorobev (University of Michigan – Dearborn)
Project: Robustness of magnetically enforced two-dimensional turbulence
Evgeny Votyakov and Egbert Zienicke (Technische Universität Ilmenau)
Project: Fine details of the local inhomogeneous external magnetic field and their manifestation in duct
flow of a liquid metal
Sotiris Kakarantzas (University of Thessaly)
Project: Natural MHD convection in cylindrical geometries
Nikos Pelekasis and Dimitrios Dimopoulos (University of Thessaly)
Project: 3D stability analysis with finite elements, of free convection rolls in a duct in the presence of a
magnetic field
Dimokratis Grigoriadis (University of Cyprus)
Project: Particle transport in MHD flows, MHD flows in complex geometries
88

Sponsored by the Institutes
Conference on
‘Computational Physics’
5-8 September 2007
89

Conferences & Schools sponsored by the Institutes
Conference on
Computational Physics
5-8 September 2007
The CCP series of conferences has become, in the course of time, the most important annual
conference gathering top-level experts in Computational Physics. It aims at confronting important
research issues in the various domains of Physics where the usage of computers has
allowed to make conceptual breakthroughs. The field has matured in the recent years and it
has developed both qualitatively, with new techniques being developed, and quantitativelyseveral
tens of thousands of researchers in Europe only. In particular, the development of density
functional techniques has allowed to model matter properties, starting time-dependent
problems, and connecting to other levels of description from the most elementary level. Generalizing
those approaches into in efficient multi-scale approaches are among the major challenges
of the field. It is worth emphasizing that CCP2007 focuses more on technical progress
based on physical approaches and approximations, rather than on possibilities offered by
nowadays large and cheap computing power available.
The main topics discussed at CCP2007 were: Electronic Structure Methods (DFT and
beyond), Quantum Monte Carlo, Materials modeling, Soft Matter and biomaterials, Phase
Transitions, Non-equilibrium Matter, MicroFluidics, Mesoscopic Modeling, Methodological
Advances, Plasmas, Computational Fluid Dynamics and Astrophysics.
Also to be noted: a session was dedicated to a presentation of a “Forward Look” study, a
strategic prospective analysis of the field under the responsibility of the European Science
Foundation. Two prize ceremonies have been held, involving IUPAP Commissions, the EPS
and CECAM.
90

Conference on Computational Physics
Conference Directors
Michel Mareschal (ULB) and Paul Geerlings (VUB)
Local Organising Committee
Jean-Marie André (FUNDP)
Marcel Arnould (ULB)
Daniel Bertrand (ULB)
Daniele Carati (ULB)
Paul Geerlings (VUB, co-director)
Marc Hou (ULB)
Jacky Lievin (ULB)
Michel Mareschal (ULB, Director)
Jean-Paul Ryckaert (ULB)
Christian van den Broeck (LUC)
International Advisory Committee
Jean-Marie André (Namur, Belgium)
Joan Adler (Haifa, Israel)
Berni J. Alder (Berkeley, USA)
Panos Argyrakis (Thessaloniki, Greece)
Norbert Attig (Jülich, Germany)
Peter Borcherds (Birmingham, UK)
Wanda Andreoni (Zurich, Switzerland)
Kurt Binder (Mainz, Germany)
Bill Camp (Sandia, USA)
Roberto Car (Princeton, USA)
Paolo Carloni (Trieste, Italy)
David Ceperley (Urbana, USA)
Giovanni Ciccotti (Rome, Italy)
Nithaya Chetty (Kwazulu-Natal, South
Africa)
Lee A. Collins (Los Alamos, USA)
Hugh Couchman
Peter Dederichs (Jülich, Germany)
Marjolein Dijkstra (Utrecht, the Netherlands)
Peter Drummond (Brisbane, South Africa)
Daan Frenkel (Amsterdam, the Netherlands)
Zhivko Genshev (Sofia, Bulgaria)
Jurgen Hafner (Vienna, Austria)
Brad L. Holian (Los Alamos, USA)
Ray Kapral (Toronto, Canada)
Tim Kaxiras (Boston, USA)
Janos Kertesz (Budapest, Hungary)
Jai Sam Kim (Korea)
Mike Klein (Philadelphia, USA)
Kurt Kremer (Mainz, Germany)
G. Gompper (Jülich, Germany)
Hardy Gross (Berlin, Germany)
James Gubernatis (Los Alamos, USA)
Alex Hansen (Trondheim, Norway)
Volker Heine (Cambridge, UK)
Renaud Lambiotte (Liège, Belgium)
David P. Landau (Georgia, USA)
Joaquin Marro (Granada, Spain)
Alejandro Muramatsu (Stuttgart, Germany)
Jaroslaw Nadrchal (Prague, Czech Republic)
Ravil Nazirov (Moscow, Russia)
Risto Nieminen (Helsinki, Finland)
Yukata Okabe (Tokyo, Japan)
Michele Parrinello (Zurich, Switzerland)
91

Conferences & Schools sponsored by the Institutes
Ramon Ravelo (El Paso, USA)
Lucia Reining (Palaiseau, France)
Ursula Röthlisberger (Lausanne, Switzerland)
Matthias Scheffler (Berlin, Germany)
Frederike Schmid (Bielefeld, Germany)
Berend Smit (Lyon, France)
Sauro Succi (Rome, Italy)
Laszlo Szunyogh (Budapest, Hungary)
Hervé Toulhoat (Rueil, France)
Julia Yeomans (Oxford, UK)
Gilles Zerah (Bruyères, France)
Shaoping Zhu (Peking, China)
Plenary Speakers
Berni J Adler (Livermore, USA)
S. Baroni (Trieste, Italy)
E. Carter (Princeton, USA)
D. Frenkel (Amsterdam, the Netherlands)
E.K.U. Gross (Berlin, Germany)
A. Georges (Palaiseau, France)
R. Kapral (Toronto, Canada)
K. Kremer (Mainz, Germany)
A. Khokhlov (Chicago, USA)
R. Lavery (Lyon, France)
R. Needs (Cambridge, UK)
S. Sanvito (Dublin, Ireland)
L. Villard (Lausanne, Switzerland)
E. Vanden-Eijnden (New York, USA)
92

Conference on Computational Physics
Invited Speakers
M. P. Allen (Warwick, UK)
R. Allen (Edinburgh, UK)
P. Argyrakis (Thessaloniki, Greece)
K. Binder (Mainz, Germany)
D. Borgis (Evry, France)
G. Bussi (Zurich, Switzerland)
P. Carloni (Trieste, Italy)
D. Ceperley (Urbana USA)
S. S. Chikatamarla (Zurich, Switzerland)
G. Courbebaisse (Lyon, France)
G. Degrez (Brussels, Belgium)
C. Dellago (Vienna, Austria)
L. Delle Site (Mainz, Germany)
H. De Raedt (Groningen, the Netherlands)
V. Ganduglia Pirovano (Berlin, Germany)
D. Garlaschelli (Siena, Italy)
P. Gaspard (Brussels, Belgium)
G. Gompper (Jülich, Germany)
X. Gonze (Louvain-la-Neuve, Belgium)
V. Heine (Cambridge, UK)
B. L. Holian (Los Alamos, USA)
W. Janke (Leipzig, Germany)
F. Jenko (Garching, Germany)
I. Karlin (Zurich, Switzerland)
J. Kermode (Cambridge, UK)
J. Kertesz (Budapest, Hungary)
S. Klapp (Berlin, Germany)
G. Kresse (Vienna, Austria)
S. Krieg (Jülich, Germany)
R. Lambiotte (Liege, Belgium)
D. P. Landau (Georgia, USA)
T. Lenaerts (Brussels, Belgium)
C. Likos (Düsseldorf, Germany)
P. G. Lind (Stuttgart, Germany)
H. Löwen (Düsseldorf, Germany)
D. MacKernan (Dublin, Ireland)
J. Marro (Granada, Spain)
J.F.F. Mendes (Aveiro, Portugal)
A. Migliore (Philadelphia, USA)
A. Milchev (Mainz, Germany)
C. Noel (Brussels, Belgium)
R. Ouared (Geneva, Switzerland)
I. Pagonabaraga (Barcelona, Spain)
M. Parrinello (Zurich, Switzerland)
Y. Peysson (Cadarache, France)
C. Pierleoni (L’Aquila, Italy)
S. Poedts (Leuven, Belgium)
N. Prasianakis (Zurich, Switzerland)
P. Proulx (Québec, Canada)
N. Quirke (London, UK)
D. C. Rapaport (Ramat-Gan, Israel)
R. Ravelo (El Paso, USA)
P. Richmond (Dublin, Ireland)
P. Rinke (Berlin, Germany)
U. Röthlisberger (Lausanne, Switzerland)
S. Rosswog (Bremen, Germany)
J.-P. Ryckaert (Brussels, Belgium)
T. Schilling (Mainz, Germany)
L. Shchur (Chernogolovka, Russia)
B. Smit (Lyon, France)
M. Sprik (Cambridge, UK)
B. Stahl (Geneva, Switzerland)
B. Tadic (Ljubljana, Slovenia)
D. Theodorou (Athens, Greece)
S. Thurner (Vienna, Austria)
A. Tröster (Vienna, Austria)
H. van Beijeren (Utrecht, the Netherlands)
T. van Erp (Leuven, Belgium)
F. Vazquez (Morelos, Mexico)
T. Wust (Georgia, USA)
J. Yeomans (Oxford, UK)
93

Sponsored by the Institutes
Conference on ‘Random and
Integrable Models in
Mathematics and Physics’
11-15 September 2007
95

Conferences & Schools sponsored by the Institutes
Random and Integrable Models
in Mathematics and Physics
11-15 September 2007
Random matrix theory has its origins in the 1920s in the works of Wishart in mathematical
statistics and in the 1950s in the works of Wigner, Dyson and Mehta on the spectra of highly
excited nuclei. Since then the subject has developed fast and has found applications in many
branches of mathematics and physics, ranging from quantum field theory to statistical mechanics,
integrable systems, number theory, statistics, probability and communication technology.
The workshop “Random and integrable models in mathematics and physics” covered the
recent advances in random matrix theory, with an emphasis on the probabilistic and physical
aspects.
Since the early 1990s, random matrix theory has produced a number of remarkable new
distribution functions in probability theory. E.g. the distribution of the largest eigenvalues of
Gaussian random matrices. Major breakthroughs came in the 90’s: connections with the fluctuations
of the length of the longest increasing subsequence of a random permutation. Also
connections with combinatorial and stochastic growth processes. Universality of these limit
laws. Problems of non-intersecting Brownian motions and limits (Dyson). Energy spectra of
quantum mechanical systems (quantum chaos), and most remarkably, in the zeros of the Riemann
zeta-function on the critical line.
These many connections have created a large and diverse community of researchers with an
interest in random matrix theory. In recent years, a number of major international meetings
were specifically devoted to random matrices. Very important were the half-year programs at
the MSRI in Berkeley («Random Matrix Models and Their Applications» in 1999), at the Newton
Institute in Cambridge («Random Matrix Approaches in Number Theory» in 2004), ETH
in Zurich («Workshop on Random Matrices», 17-21 May 2005), CRM in Montreal («Random
Matrices, Random Processes and Integrable Systems», 20 June-8 July 2005), etc…
It is important to point out that the US National Science Foundation has identified “random
matrix theory and its ties to classical analysis, number theory, quantum mechanics, and coding
theory’’ as one of its emerging areas. Also two of the 10 plenary lectures at the 2006
International Congress of Mathematicians in Madrid are devoted to random matrix theory
(Percy Deift and Iain Johnstone).
96

Random & Integrable Models in Mathematics and Physics
The workshop in Brussels was ideal to continue these activities. The meeting brought together
a number of experts on the diverse aspects of random matrix theory. The participation of
young researchers at the post-doctoral and pre-doctoral levels who are currently involved in
research activities related to random matrices was encouraged.
Specific themes included
o
o
o
o
o
o
Eigen values of random matrices.
Matrix-valued stochastic processes.
Statistical mechanical models.
Quantum chaos.
Free probability theory.
Multivariate statistics
Scientific Committee
Boris Dubrovin (SISSA/ISAS, Trieste, Italy)
Robbert Dijkgraaf (Universiteit van Amsterdam, the Netherlands)
Luc Haine (UCL, Belgium)
Marc Henneaux (ULB, Belgium)
Arno Kuijlaars (K.U.Leuven, Belgium)
Nicolai Reshetikhin (Berkeley, USA)
Pierre van Moerbeke (UCL, Belgium)
Organising Committee
Peter Bueken (HZS, Belgium)
Marc Henneaux (ULB, Belgium)
Pierre van Moerbeke (UCL, Belgium)
Pol Vanhaecke (Poitiers, France)
97

Conferences & Schools sponsored by the Institutes
Invited Speakers
Mark Adler (Brandeis University, Waltham,
USA)
Gerard Ben Arous (Courant Institute, New-
York, USA)
Marco Bertola (Université Concordia, Montreal,
Canada)
Pavel Bleher (Indiana University /Purdue University,
Indianapolis, USA)
Philippe Di Francesco (Saclay, Gif-sur-Yvette,
France)
Boris Dubrovin (SISSA/ISAS, Trieste, Italy)
Robbert Dijkgraaf (Universiteit van Amsterdam,
the Netherlands)
Bertrand Eynard (SPHT, Saclay, Gif-sur-Yvette,
France)
Patrik Ferrari (Weierstrass Institut, Berlin, Germany)
Tamara Grava (SISSA/ISAS, Trieste, Italy)
Alberto Grunbaum (University of California,
Berkeley, USA)
John Harnad (Centre de recherches mathématiques
and Université Concordia, Montreal,
Canada)
Alexander Its (Indiana University /Purdue
University, Indianapolis, USA)
Kurt Johansson (Sveriges Största Tekniska
Universitet, Stockholm, Sweden)
Thomas Kriecherbauer (Ruhr-Universität, Bochum,
Germany)
Ken McLaughlin (University of Arizona, Tucson,
USA)
Marta Mazzocco (University of Manchester,
United Kingdom)
Brian Rider (University of Colorado, Boulder,
USA)
Toufic Suidan (University of California, Santa
Cruz, USA)
Johan van de Leur (Rijksuniversiteit Utrecht,
the Netherlands)
Alexander Veselov (Loughborough University,
UK)
Harold Widom (University of California, Santa
Cruz, USA)
Paul Wiegmann (University of Chicago,
USA)
Paul Zinn-Justin (Université Paris XI, France)
98

Random & Integrable Models in Mathematics and Physics
Comparison with some known exact
results
Let us compare this asymptotics with some
known exact results. There are cases, for which
the model has been solved earlier by different
methods: the free fermion line and A(1), A(2),
A(3), one, two, and three enumeration of alternating
sign matrices (ASM).
b/c
F
D
1 A(1)
A(2)
AF
A(3)
F
0 1
a/c
Phase diagram.
15
99

100

Quantum Field Theory,
Strings and Gravity
14-31 October 2007
101

Conferences & Schools sponsored by the Institutes
102

In 2007, the second edition of the Amsterdam-
Brussels-Paris Doctoral School on “Quantum
Field Theory, Strings and Gravity” was organized
again with the partial support of the
International Solvay Institutes. The aim of the
school is to provide first-year PhD students
with advanced courses that help bridge the
gap between Master-level courses and the
most recent advances in the field. Responsible
for the organization as well as for teaching
the courses are ULB, VUB, the University
of Amsterdam and various institutions in Paris
led by Ecole Normale Supérieure. The school
serves as a module of the FNRS doctoral thematic
school “Physique et Astrophysique” in
the “Communauté Française de Belgique”.
The school consisted of three weeks of lectures
in Paris, three weeks in Brussels and
three weeks in Amsterdam, with a one-week
break between the segments. This way, the
students are exposed to several institutes,
each with their own research and teaching
culture, and to professors from the various
institutes. Last but not least, they get to meet
fellow students from neighboring institutes
and countries, who will be their peers and
colleagues throughout (and possibly beyond)
their PhD studies.
Quantum Field Theory, Strings and Gravity
Doctoral School
Quantum Field Theory, Strings
and Gravity 14-31 October 2007
This year, the school had eighteen first-year
PhD students, seventeen of whom attended
the Brussels segment of the school. (The numbers
were somewhat higher in 2006 because
that first edition of the school was attended by
both first and second year students.) In addition
to the organizing universities, the neighboring
institutes K.U.Leuven, Utrecht University
and Saclay sent students to take part in
the school. In total, seven students came from
the Paris area, eight from Belgium and three
from the Netherlands.
An anonymous survey at the end of the school
made it clear that the participants considered
the school very useful and an essential part of
their PhD training. This encourages the Solvay
Institutes to continue to support the school in
the coming years. The survey has also led to
some useful suggestions for small changes to
the coverage of topics, which we intend to
implement in future editions. The possibility
to include additional institutions, which have
expressed interest in becoming part of the
school, will certainly be seriously considered,
although it is our intention to keep the teaching
in Paris, Brussels and Amsterdam, a format
that seems to work very well.
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104

Sponsored by the Institutes
Experimentarium:
Lecture by Michael Berry
23 October 2007
105

Conferences & Schools sponsored by the Institutes
Seven Wonders of Physics
23 October 2007
Professor Michael Berry
On 22-23 October, the Science Museum of ULB (Experimentarium) organized
an “open door event”. Professor Michael Berry concluded the event
with a public lecture attended by more than 150 persons.
Abstract
“Sometimes, nature illustrates the abstract ideas of physics and mathematics in beautiful
ways, and the ideas can be brought to life by simple demonstrations. My seven
wonders include the great moon-driven river wave, light interference magnified in
rainbows, quantum twists and turns, and the colour of gold.”
106

Experimentarium
107

108

Sponsored by the Institutes
Seminars and Visitors
109

Seminars
Seminars
The list includes the seminars, discussion groups and journal clubs co-organized
by the International Solvay Institutes and the Service de Physique Théorique et
Mathematique of the ULB, the Theoretical Particle Physics Group of the VUB and
the High Energy Physics and Relativistic Field Theory Group of the K.U.Leuven.
1. Kac-Moody Algebras and Controlled
Chaos, Daniel Wesley (Cambridge
University, UK) – February 7, 2007.
2. Pseudo supersymmetry: a tale of
alternate realities, Dieter Van Den Bleeken
(K.U.Leuven, Belgium) – February 14, 2007.
3. Marco Zagermann (MPI München,
Germany) – February 14, 2007.
4. Perspectives of white noise analysis,
Takeyuki Hida (Meijo University, Japan)
and Poisson noise, infinite symmetric
group and stochastic integrals based on
the quadratic Hida distribution, Si Si (Aichi
Prefectural University, Japan) – February 20,
2007.
5. KK-monopoles as giants gravitons
in AdS_5xS^5, Bert Janssen (Universidad
de Granada, Spain) – February 21, 2007.
6. Trivializing the conifold’s base, Jarah
Evslin (ULB, Belgium) – February 21,
2007.
7. Bootstrap in Supersymmetric
Liouville Field Theory, Alexander Belavin
(Landau Institute, Russia) – March 7,
2007.
8. The Universe as a Topological Defect,
Andres Anabalon (Centro de Estudios
Cientificos, Chile) – March 21, 2007.
9. Gravity with zero metric and dark
matter, Max Bañados (Pontificia Universidad
Católica de Chile, Chile) – March 28,
2007.
10. Chiral symmetry breaking as
open string tachyon condensation, Roberto
Casero (Ecole Polytechnique, France)
– March 28, 2007.
11. Pure type I supergravity and
DE(10), Christian Hillmann (AEI Potsdam,
Germany) – April 18, 2007.
12. A string dual perspective on quarkgluon
plasmas of QCD-like theories, Jose
Edelstein (Universidad de Santiago de Compostela,
Spain) – April 18, 2007.
13. Anti-de Sitter black holes, Harvey
Reall (University of Nottingham, UK) – April
25, 2007.
14. Non-geometric fluxes as supergravity
backgrounds, Fernando Marchesano
(LMU München, Germany) – May 2,
2007.
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Seminars
15. Chaos, Compactification and
Coxeter Groups, Daniel Persson (ULB, Belgium)
– May 2, 2007.
16. Non-local SFT Tachyon and Cosmology,
Alexey Koshelev (University of
Crete, Greece) – May 16, 2007.
17. On supersymmetry breaking in
string theory from gauge theory in a
throat, Sameer Murthy (ICTP Trieste, Italy)
– May 16, 2007.
18. Higher-spin Chern-Simons theories,
Olaf Hohm (Utrecht Universiteit, the Netherlands)
– May 23, 2007.
19. Non-renormalization theorems in
type II string theory and maximal supergravity,
Jorge Russo (Universidad de Barcelona,
Spain) – May 23, 2007.
20. Metastable Supersymmetry Breaking
and Gauge/Gravity Duality,
Riccardo Argurio (ULB, Belgium) – May
30, 2007.
21. Phases of higher-dimensional black
holes, Roberto Emparan (Universidad de Barcelona,
Spain) – May 30, 2007.
22. An E_9 multiplet of BPS states,
Laurent Houart (ULB, Belgium) – June 6,
2007.
23. Cascading quivers from decaying
D-Branes, Stanislav Kuperstein (ULB, Belgium)
– June 6, 2007.
24. All-order symmetric subtraction
of divergences for massive Yang-Mills
theory based on nonlinearly realized
gauge group, Andrea Quadri (Università
degli Studi di Milano, Italy) – June 13,
2007.
25. A symmetry approach to viruses,
Anne Taormina (Durham University, UK)
– September 26, 2007.
26. Constrained E10 Geodesics
and Supergravity, Axel Kleinschmidt
(ULB, Belgium) – October 10, 2007.
27. Magnetic Fields in the Universe,
Hector Rubinstein (Stockholms Universitet,
Sweden) – October 10, 2007.
28. Phase structure of higher-dimensional
black rings and black holes,
Niels Obers (Niels Bohr Institute, Denmark)
– October 17, 2007.
29. First-order flow equations for extremal
black holes in very special geometry,
Jan Perz (K.U.Leuven, Belgium) – October
24, 2007.
30. K(E9) and the fermionic sector of
maximal supergravity, Jakob Palmkvist
(AEI Potsdam, Germany) – October 24,
2007.
31. Lie superalgebras associated to
supergravity backgrounds, Jose
M. Figueroa-O’Farrill (University of
Edinburgh, UK) – October 31, 2007.
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Seminars
32. Hints for QCD from strings in five
dimensions, Aldo Cotrone (K.U.Leuven,
Belgium) – October 31, 2007.
33. The nature of generic singularities
in general relativity, Claes Uggla
(Karlstads Universitet, Sweden) – November
7, 2007.
34. Constraints on extremal self-dual
CFTs, Matthias Gaberdiel (ETH Zürich,
Switzerland) – November 7, 2007.
35. Spinor helicity methods in N=0 and
N=8 Supergravity, Dan Freedman (RPI
New-York, USA) – November 14, 2007.
36. Singletons, Anti-Singletons and
Higher-Spin Master Fields, Carlo Iazeolla
(INFN Roma, Italy) – November 14, 2007.
37. Some aspects of the Gauge-Strings
Duality, Carlos Nuñez (Swansea University,
UK) – November 21, 2007.
38. Backreacting Flavors in the Klebanov-Strassler
Theory: a New Duality Cascade,
Stefano Cremonesi (SISSA Trieste,
Italy) – November 21, 2007.
39. An improved holographic model
for QCD, Elias Kiritsis (CPHT Palaiseau,
France) – November 28, 2007.
40. Mesons and mesinos from AdS/
CFT, Ingo Kirsch (ETH Zürich, Switzerland)
– November 28, 2007.
41. No-scale SUSY-breaking and soft
terms with torsion, Pablo Camara (CPHT
Palaiseau, France) – December 5, 2007.
42. Resolving Gravitational Singularities,
Finn Larsen (Michigan University,
USA and CERN Geneva, Switzerland) – December
5, 2007.
43. Penrose Limits and Plane Waves
– Geometry and String Theory Aspects,
Sebastian Weiss (Université de Neuchâtel,
Switzerland) – December 12, 2007.
44. E(7) and d=11 supergravity, Christian
Hillman (AEI Potsdam, Germany) – December
12, 2007.
112

Visitors
Visitors
Numerous scientists came to Brussels in the context of the 21st Solvay Conference on
Chemistry, the Colloquia, Workshops, Seminars or Research Programs sponsored by the
Institutes. Their names are listed in the sections dedicated to these activities.
The Institutes are also developping an active visitors program to support international
research collaboration.
Jim Hartle’s quote (University of Santa Barbara, USA)
19-29 July 2007
“Our collaboration to study the origin of classicality from the no-boundary theory of the
universe’s quantum state was helped by my visit to the Solvay Institutes in July 2007 to
work with Thomas Hertog. International collaboration of this kind is becoming increasingly
frequent in contemporary science, and the Solvay Institutes can play a significant
role in fostering that through visits of this kind.”
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Visitors
Cooperation Agreements
Centro de Estudios Científicos (Valdivia, Chile)
January: A delegation of the International Solvay Institutes took part in the official inauguration
of the Centro de Estudios Científicos by Mrs Michelle Bachelet, President of Chile.
La Tercera, Chile, January 14, 2007 p. 27
114

Visitors
Visits of Chilean Scientists
Mr. Andrés Anabalón (CECS), 20 March – 12 May 2007
Prof. Max Bañados (PUC), 26-31 March 2007
Prof. Andrés Gomberoff (Universidad Andrés Bello), 26-31 March 2007
Prof. José Edelstein (CECS), 16-18 April 2007
Joint publications
C. Bunster, M. Henneaux – A Monopole Near a Black Hole – PNAS (USA) 104: 12243-
12249, 2007 – [e-Print Archive: hep-th/0703155].
G. Barnich, A. Gomberoff – Dyons with Potentials: Duality and Black Hole Thermodynamics
– e-Print Archive: 0705.0632.
Lebedev Physical Institute (Moscow, Russia)
Visits of Russian Scientists
Prof. Maxim Grigoriev (Lebedev Institute), 27 May – 2 June 2007
Prof. Alexander Belavin (Landau Institute), 5-8 March 2007
115

116

Sponsored by the Institutes
RESEARCH ON GRAVITATION,
STRINGS AND COSMOLOGY
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Research on Gravitation, Strings & Cosmology
Researchers
Permanent Members
Riccardo Argurio (ULB)
Glenn Barnich (ULB)
Ben Craps (VUB)
Frank Ferrari (ULB)
Marc Henneaux (ULB)
Thomas Hertog (Paris VII)
Laurent Houart (ULB)
Axel Kleinschmidt (ULB)
Christiane Schomblond (ULB)
Alexander Sevrin (VUB)
Postdoctoral Members
Mohab Abou Zeid (VUB)
Francesco Bigazzi (ULB)
Oleg Evnin (VUB)
Jarah Evslin (ULB)
Emiliano Imeroni (ULB)
Alexey Koshelev (VUB)
Chethan Krishnan (ULB)
Stanislav Kuperstein (ULB)
Carlo Maccaferri (ULB)
Doctoral Students
Alice Bernamonti (VUB)
Nazim Bouatta (ULB)
Cyril Closset (ULB)
Geoffrey Compère (ULB)
François Dehouck (ULB)
Frederik De Roo (VUB)
Ella Jamsin (ULB)
Daniel Persson (ULB)
Wieland Staessens (VUB)
Nassiba Tabti (ULB)
Dimitri Terryn (VUB)
Cedric Troessaert (ULB)
Vincent Wens (ULB)
Alexander Wijns (VUB)
Research Summary
General framework
The standard model of particle physics is
based on quantum field theory, a framework
that reconciles Poincaré invariance with
quantum mechanics and allows one to understand
the electromagnetic and the two types
of nuclear interactions. The fourth fundamental
interaction, gravitation, is described
by Einstein’s theory of general relativity. Experiments
as well as theoretical arguments
indicate that neither the standard model, nor
general relativity can be complete.
Purely theoretical attempts at generalizations
are constrained, of course, by mathematical
consistency and the need to incorporate the
previous theories in the domains where they
have been successful. Additional guiding
principles are needed, though. Symmetry is
such a principle and pervades most of the research
carried out in theoretical high energy
physics.
The Yang-Mills type theories for the three microscopic
forces of elementary particle physics
are invariant under Poincaré symmetries,
the symmetry group of flat space-time. These
theories admit in addition certain internal symmetries
known as gauge symmetries. In general
relativity, gravitation arises when going
from a flat to a curved spacetime, and Poincaré
symmetries become part of the gauge
group of diffeomorphisms.
In models that go beyond the existing theories,
other symmetries come to the front.
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Supersymmetry
Supersymmetry is a natural extension of Poincaré
symmetry in the presence of fermionic
matter fields. Supersymmetric extensions of
the standard model will be tested at the experiments
planned in the Large Hadron Collider
at CERN in Geneva.
Supersymmetry is also an important ingredient
of string theory, a model for unification
of the four fundamental interactions and for
a microscopic formulation of gravity. At low
energy, higher dimensional theories of gravitation
emerge that include supersymmetry as
part of their gauge group together with supersymmetric
extensions of Yang-Mills gauge
theories.
In supersymmetric situations, these dualities
become tractable. Finally, dualities between
different string theories as well as holographic
duality between gauge and gravity theories
feature prominently in most of the recent developments
in string theory.
Hidden symmetries
Hidden symmetries in gravity and string theory
arise in compactifications of supergravity
theories and among the string duality groups.
The algebraic structure of these symmetries
is related to infinite-dimensional Lorentzian
Kac-Moody algebras, in particular those of
E 10
and E 11
.
Dualities
One of the first theoretical extensions of Maxwell’s
theory of electromagnetism has been
the inclusion of magnetic sources. The introduction
of such sources is motivated by the
desire to preserve invariance under duality
rotations, a symmetry of the source-free equations.
The solution that is dual to the Coulomb
solution describing a static point-particle electron
is a magnetic monopole. In some sense,
black hole solutions in gravitational theories
are the analog of the Coulomb solution to
Maxwell’s theory.
In nonlinear theories like Yang-Mills theories,
dualities relate a strongly coupled regime to
one at weak coupling, where standard perturbative
computations may be performed.
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Research on Gravitation, Strings & Cosmology
Research carried out in 2007
Supersymmetric Gauge Theories
Since consequences of supersymmetry are
not observed at energy scales that are presently
accessible, an important theoretical
question is how supersymmetry is broken at
low energy scales. Part of the research carried
out has been devoted to dynamical supersymmetry
breaking, i.e., supersymmetry
breaking at the non-perturbative level. We
have constructed supersymmetry breaking
models with relevant gauge sectors and analyzed
their coupling to gravity. Their embedding
in full-fledged string theory realizations
has also been studied.
We have also continued our work on exactly
solving supersymmetric quantum Yang-Mills
models using string theoretic dualities.
D-branes
An important ingredient of string theory are
D-branes. We have studied the geometry of
these objects in both geometric and non-geometric
string compactifications. In particular,
we have developed a manifestly supersymmetric
worldsheet description of certain types
of D-branes. In addition, we have studied aspects
of D-brane recoil.
have also improved our understanding of
the Taub-NUT spacetime, the gravitational
analog of the magnetic monopole. We have
shown how to resolve the string singularities
of dyons, solutions which carry both electric
and magnetic charge, and developed a
framework to complete our understanding of
the thermodynamics of dyonic black holes.
Hidden Symmetries of Gravity
Hidden symmetries are a major research
theme of several members of our group. We
have produced on the one hand a detailed
review of this connection in the BKL limit of
supergravity theories, i.e., near a spacelike
singularity. On the other hand, we have used
such symmetries in order to construct new solutions
of 11 dimensional supergravity.
Cosmology
We have studied several string theory models
of cosmological singularities. On the one
hand, we have developed techniques to deal
with Hamiltonians with isolated singularities in
their time dependence, which may be useful
in the study of big bang models in matrix theory.
On the other hand, we have performed
a detailed analysis of a big crunch/big bang
model in the context of the AdS/CFT correspondence.
We have also started research
on dark energy.
Electromagnetic Duality
As part of our research effort in the context
of electromagnetic and gravitational dualities
we have studied what happens when a
monopole is absorbed by a black hole. We
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Research on Gravitation, Strings & Cosmology
Research Interests
of some Members
Axel Kleinschmidt
Physique Théorique et Mathématique – ULB
Symmetries and String Theory
Importance of Symmetries
Progress in theoretical physics is intimately
linked to the discovery of widely applicable
principles which, rather than explaining specific
phenomena, capture essential structures
common to many problems from different
areas in physics. Arguably many of the most
powerful such principles are related to symmetries.
A physical system or model is said to possess
a certain symmetry if there exist superficially
distinct descriptions which can be
transformed into one another by a symmetry
transformation. As a concrete example
one may consider the classical problem of
describing the force exerted on an electron
by a single proton which is fixed at a given
point in the laboratory. The strength of the
electromagnetic Coulomb force depends
only on the distance between the electron
and the proton; as long as this distance is
kept fixed the strength does not change when
the electron is moved around (the direction
does change and always points towards
the proton). All points of equal distance from
the proton lie on the surface of a sphere and
the associated problem is said to possess
spherical symmetry. If this symmetry
is exploited when solving the resulting
motion of the electron the equations
simplify substantially. This illustrates
why symmetries are so important: They
typically lead to large simplifications in the
equations and often are crucial for allowing
a solution of these equations.
String Theory and Gravity
Despite the general importance of symmetries
there exist many theories for which the underlying
symmetries have not been fully uncovered.
To this class belong string theory and
the theory of general relativity. The latter is
known to describe very well gravitational
processes whereas the former is thought
to explain the unification of gravity with the
other three fundamental forces in a quantum
theory — one of the outstanding challenges
of modern physics. It is the general subject of
my research to obtain a better understanding
of the symmetry structures in these cases.
At low energies, the various string theories can
be replaced by effective field theories which
consist of gravity coupled to very specific types
of matter. It is one of the distinguishing, and most
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Research on Gravitation, Strings & Cosmology
puzzling, features of these theories that they exhibit
hidden symmetries when subjected to the process of
so-called dimensional reduction. These hidden symmetries
are not apparent in the usual formulation of
the theory and are, furthermore, very closely linked
to the beautiful subject of exceptional semi-simple
finite-dimensional Lie algebras in mathematics. The
precise origin of this relation is unclear but the existence
of hidden symmetries after dimensional reduction
suggests that they should play a central role in
the construction of string theory.
Space-like Singularities and Kac–Moody
Algebras
One of the major deficiencies in our current understanding
of gravity and string theory is the way how
space-time behaves near space-like singularities
such as the big bang. The conventional formalism
breaks down in such a situation, thereby signalling
the need for a different formulation of quantum gravity.
Research carried out at the International Solvay
Institutes and IHES, France, has revealed that, even
though the full model is not understood, the dominant
part of the dynamics near a space-like singularity
is concisely captured by a so-called cosmological
billiard. In this picture the evolution of space-time is
described by the motion of an imagined billiard ball
on a billiard table of unusual shape. Every time the
ball is reflected off a wall of this table, there is drastic
change in the expansion or contraction of space.
One of the surprising outcomes of this analysis was
that the shape of the billiard table is related directly
to the theory of hyperbolic Kac–Moody Lie algebras,
a subject generalising that of the exceptional
Lie algebras mentioned above. This gave further support
for the importance of such symmetry structures
for the understanding of gravity and string theory.
The most interesting of these hyperbolic Kac–
Moody algebras is denoted by E 10
and is the one
arising from low energy string theory. This is a very
rich, infinite-dimensional structure which contains
more information than only that of the shape of the
billiard table. It can be shown that also the remaining
structure has a very close connection to low
energy string theory and also incorporates one of
the most central desiderata of modern M-theory (the
successor of string theory), namely the unification of
different string models.
E 10
: A New View on Space-Time?
Postulating that E 10
be a fundamental symmetry of
a unifying theory leads to drastic implications on
the way space-time is viewed. One can replace
the equations of gravity and low energy string
theory by an infinite set of equations which exhibits
manifest E 10
symmetry and it was shown that this
replacement is valid very close to the space-like
singularity. The status of the validity of this replacement
as one moves away from the singularity is
less clear and one of the most important questions
of my research. If there is an extended validity of
this replacement or a smooth transition from the
conventional description to the E 10
description one
can think of space as a de-emerging concept in
the approach to the singularity. The very notions of
space and direction would be replaced by more
algebraic concepts derived from E 10
. At the same
time this might allow for an understanding of quantum
gravity in such situations.
On the way to realising this far-reaching proposal
many points have to be investigated. They represent
important consistency checks on the ideas outlined
above.
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Research on Gravitation, Strings & Cosmology
One of the central questions is that of the nature
of the singularity itself: Do singularities
exist from the point of view of an E 10
model?
Or is there a resolution of the singularity as
is often argued from string theory? By resolution
one means that many of the meaningless
results of conventional computations turn into
meaningful quantities since the singular part
of the answer disappears. From a string theory
perspective such a resolution could arise
from high energy modes of the string which
cannot be ignored in a full model. There have
been preliminary studies of the effect of such
modes on the E 10
picture with promising but
not unambiguous results. If their effect in E 10
can be made precise this will lead to predictions
for string theory itself since the computations
of such modes is a notoriously hard
problem there.
bosons and fermions but which leaves many
issues unresolved. In particular, the question
of local supersymmetry in this generalised
E 10
model requires attention; the extension to
the gauged case just discussed also awaits
exploration.
As indicated already in the beginning, it is
an outstanding open problem of theoretical
physics to construct a consistent theory of
quantum gravity. It is hoped that some of the
proposals presented here will contribute to
the construction of such a theory.
Another question concerns the rigidity of the
proposal: In low energy string theory there
are deformations of the couplings of matter
and gravity and of the symmetry structure of
the model. These so-called gauged (or massive)
supergravities form an integral part of
the landscape of string theory models and
therefore should be describable in E 10
language
as well. Does this require a modification
of the E 10
structure or are these cases
already accounted for in the present proposal?
If there is a modification what are the
mathematical properties of the new symmetry
structure?
A characteristic feature of string theory and of
its low energy limit is the presence of both fermionic
and bosonic particles. There is a generalised
E 10
model which also deals with both
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Research on Gravitation, Strings & Cosmology
Thomas Hertog
Thomas Hertog is chercheur at the CNRS (Centre Nationale de la Recherche Scientifique) affiliated
with the “Laboratoire AstroParticule et Cosmologie” in Paris, and Associate Member of the
Solvay Institutes. His current research interests include theoretical cosmology and string theory,
the foundations of quantum cosmology and gravitational physics in general.
Hertog obtained his PhD from the University of Cambridge in 2001. He worked for several
years as a postdoctoral researcher first at the University of California (Santa Barbara) and then
at CERN, before taking up a position in Paris in 2007.
Introduction
The Big Bang singularity is one of the most
vexing and profound puzzles in modern cosmology,
as many of the predictions in cosmology
rest on a set of ad hoc assumptions
at the beginning. In the absence of a theory
that describes the conditions at the Big Bang,
therefore, cosmology as a science remains
fundamentally incomplete.
General Relativity breaks down at the Big
bang. Hence a predictive framework for cosmology
must presumably be based on quantum
gravity, where one expects that the classical
singularity is replaced by a quantum state.
A priori, it seems plausible that in quantum
gravity the universe can be in a range of different
quantum states. Each state would provide
a different resolution of the classical singularity,
in the sense that this would no longer
be an obstacle to prediction in cosmology.
One might then hope that future observations
- particularly those of CMB anisotropies - will
enable us to determine which quantum state
is physically realized.
During this year we have pursued two different
approaches towards the formulation
of a quantum state of the universe. We have
also begun to study what are the generic properties
of our specific universe if it is in one of
these states. We now briefly describe both.
Holographic Cosmology
The first approach, which we have pursued in
collaboration with Ben Craps of the Solvay
Institutes and with Neil Turok of the University
of Cambridge, goes back to earlier work in
collaboration with Gary Horowitz.
It is based on the anti-de Sitter/conformal field
theory (CFT) duality in string theory, which
holographically relates quantum gravity on
asymptotically anti-de Sitter (AdS) spacetimes
to certain gauge theories defined on the fixed
boundary spacetime. The AdS/CFT duality
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Research on Gravitation, Strings & Cosmology
provides, via the gauge theory description,
a nonperturbative definition of string theory.
This can be generalized to spacetimes that
exhibit a cosmological dynamics – and hence
an initial big bang singularity. With Horowitz
we had shown that this generalization of the
AdS/CFT duality relates the problem of understanding
the dynamics near cosmological
singularities, to that of understanding the dynamics
of field theories with unstable scalar
field potentials. Cosmological singularities on
the gravity side correspond in the dual theory
on the boundary to a scalar field rolling to infinity
in finite time, at first sight leading to a loss
of probability.
This year, in collaboration with Ben and Neil,
we have further developed this holographic
description of the cosmology. In particular
we have shown that one can generalize the
method of self-adjoint extensions to define consistent
unitary quantum evolution in the boundary
theory. This has led to what I believe is currently
one of the most promising approaches
we have to study the quantum nature of cosmological
singularities in string theory.
Remarkably, the dual field theory evolution
indicates the Big Bang need not be the beginning.
Indeed, we find there exist a class
of wave packets in the boundary theory for
which the quantum spread of the wave function
for the homogeneous mode suppresses
the creation of high energy particles as the
scalar field rolls down the potential, allowing
the wave packet to bounce back. This leads
to the prediction that on the gravity side, a
quantum transition from the big crunch to a
big bang is the most probable outcome of
cosmological evolution, at least for this class
of states.
The AdS/CFT duality relates string theory inside
the AdS cylinder to gauge theory on the boundary.
No-Boundary Cosmology
The second approach, which we have pursued
in collaboration with James Hartle of
the University of California and with Stephen
Hawking of the University of Cambridge,
goes back to earlier work of Hartle and
Hawking in which they boldly put forward
a concrete proposal for the quantum state
of the universe. Their proposal is known as
the no-boundary state, since it associates to
each possible history for the universe a complex
geometry without boundary that is used
to calculate the relative probability of that
history. Although the mathematical foundations
of the no-boundary proposal are rather
weak, it provides an excellent framework to
illustrate and develop the predictive power
- and hence the central role - of a quantum
state for the universe in cosmology.
During this year we have in particular been
investigating how and when classical spacetime
emerges from the no-boundary theory of
the universe’s quantum state. The wide range
of time and place on which the Einstein’s
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Research on Gravitation, Strings & Cosmology
classical deterministic laws of spacetime geometry
hold is without doubt a prominent
observational feature of our indeterministic
quantum universe. Spacetime behaves classically
on familiar scales over the whole of the
visible universe and from a short time after the
big bang to the far future. But just as classical
behavior for a particle is not implied by every
state in non-relativistic quantum mechanics,
classical behavior is not implied by every
quantum state of the universe in a quantum
theory of gravity.
In collaboration with Hawking and Hartle, we
have shown in a simple model that if the universe
is in the no-boundary state, all histories
that behave classically at late times must undergo
a significant period of inflation at early
times. The no-boundary wave function, therefore,
is consistent and indeed to some extent
explains the standard cosmological model.
We have further shown how there is a significant
probability that the universe `bounced’
in the past at a minimum radius well below the
Planck density, rather than have a classically
singular beginning. Interestingly it appears
that in the most probable bouncing histories
in the no-boundary state the thermodynamic
arrow of time points away from the bounce
on either side. This is in sharp contrast with the
causality of the holographic cosmologies discussed
above, where the arrow of time points
in the same direction everywhere.
Future Prospects
The study of the Big Bang is by no means a
purely academic issue. Indeed, the remnants
of the early quantum gravitational phase are
encoded in the microwave spectrum of anisotropies;
the details of these spectra depend
on the quantum state, thus providing an observational
discriminant between different
theories. It is therefore essential to calculate
the primordial spectra of fluctuations predicted
by each of the quantum states above, and
confront these predictions with observation.
In the case of holographic cosmology, it is intriguing
that the instability and approximate
scale-invariance of the boundary theory
automatically lead to the generation of an
approximately scale-invariant spectrum of
stress-energy perturbations on the boundary,
whose amplitude is suppressed by the asymptotically
free coupling. One key project for
2008, therefore, will be to see whether these
are properties of the spectra on the gravity
side too.
Any quantum state of the universe selects a particular
ensemble of histories, each with its own probability. In
the most probable histories in the quantum states we
have investigated, the big bang is nothing but a transition
from contraction to expansion. However, whereas
in holographic cosmology the dominant cosmology
has an arrow of time that always points forward, the
no-boundary state predicts the thermodynamic arrow
of time reverses at the big bang.
126

Research on Gravitation, Strings & Cosmology
Oleg Evnin
Theoretical Particle Physics – VUB
Evolution across cosmological singularities
The theory of Big Bang arose in 1920es following
Edwin Hubble’s observation that distant
galaxies appear to be flying away from
us with a speed roughly proportional to how
far away they are. This would suggest that the
Universe is expanding uniformly. Extrapolated
back in time according to the known laws
of gravity, this expansion would imply that,
some 10-20 billion years ago, the Universe
started out from a «single point». Of course,
such naive extrapolation will have to break
down, but the general expectation that, in the
past, there was a period of extremely «small»,
dense and hot Universe has become known
as the theory of the Big Bang.
The notion of Big Bang has been given further
credibility in 1960es with the discovery of the
Cosmic Microwave Background radiation.
This electromagnetic radiation distributed
over the sky with a nearly perfect uniformity
can be elegantly explained as a relic survivor
of the epoch when the Universe was a thousand
times smaller than it is now. Should this
explanation be taken seriously, it would imply
that the reverse extrapolation of the galactic
expansion works at least until the time when
the Universe was 1/1000 of its present size.
One kind of cosmological scenarios which
has received a large amount of attention
from cosmologists is the so-called inflationary
universe. In its latest version, this approach
assumes that the Universe has existed forever,
and, occasionally, a part of it would undergo
ultra-rapid expansion, followed by «re-heating»,
which would create a hot dense region
of the Universe associated with the Big Bang.
This region would further expand and gradually
transform into the visible Universe as we
know it.
Some problems with the inflationary models
have been pointed out by cosmologists, but,
even from a purely theoretical perspective, it
would be interesting to consider a different
class of scenarios, whereby the Universe actually
does shrink infinitely (as we look further
and further in its past), and there is a «beginning»
of or, at least, a special point in time.
The reason for venturing into this territory is
that it confronts us sharply with fundamental
questions on the nature of space-time. It has
been an unresolved high-profile problem in
theoretical physics for decades to construct
the so-called «quantum theory of gravity»
which would tell us what happens to the fabric
of space-time at tiny distances (which are
roughly as small compared to the atomic nucleus
as the atomic nucleus is small compared
to us) or at extreme conditions (such as the
127

Research on Gravitation, Strings & Cosmology
tiny near-Big Bang Universe). Thus the questions
of quantum gravity come to the center
of investigations, once we turn to cosmological
scenarios featuring an infinite contraction
of the Universe in the past, and, furthermore,
such cosmological scenarios can be used as
a touchstone for our notions of the structure of
space time.
A few different approaches to quantum gravity
have been formulated over the last few
decades: none fully satisfactory, and some
more promising than the others. The objective
of our research at VUB and the Solvay Institutes
has been to examine the possibilities
for treatment of a certain class of space-time
singularities (similar, though not exactly identical
to those relevant for cosmology) within
a few different approaches to quantum gravity.
It has been an important realization that
a certain mathematical structure («quantum
Hamiltonians with a singular time dependence»)
makes an appearance in a number
of different contexts when the problem of dynamical
evolution in the singular space-time
region is considered. Our recent efforts have
concentrated on exploring this mathematical
structure and examining the range of opportunities
it presents for treating the problem
of cosmological singularities. Of particular
interest is the question of whether the history
of a universe can be extended beyond the
point of infinite compression - hence, «evolution
across singularities.»
We intend to pursue this direction of research
further trying to work out the qualitative consequences
of such singularity transitions within
the framework of the existing/conjectured
theories of quantum gravity. At this point, it
would probably be too bold to expect fullfledged
cosmological scenarios coming out
of these activities, given the theoretical uncertainties.
However, and perhaps more advantageously,
one can turn the issue around and
try to resolve some of the theoretical uncertainties
by considering different putative cosmological
scenarios.
128

Research on Gravitation, Strings & Cosmology
Invited Talks at Conferences,
Seminars and Schools
1. January 11, 2007: Ben Craps, “Recoil of
low-dimensional D-branes” - Imperial College
London, UK.
9. March 6, 2007: Glenn Barnich,
“Symmetries in Gauge Theories: Central
extensions in flat spacetimes-Thermodynamics
of black holes dyons” - Scuola Normale
Superiore, Theoretical Physics Group, Pisa,
Italy.
2. January 11, 2007: Marc Henneaux, “Symmetries
and Fundamental Forces” - Universidad
Andrés Bello, Santiago, Chile.
3. January 18, 2007: Thomas Hertog, “To
Bounce or not to Bounce” - Workshop on the
“Quantum Nature of Spacelike Singularities”
- KITP, Santa Barbara, USA.
4. February 5, 2007: Ben Craps, “Recoil of
low-dimensional D-branes” - Max-Planck-Institut,
Munich, Germany.
5. February 15, 2007: Marc Henneaux,
“Symétries et forces fondamentales“ - Seminar
“filière physique polytechnique“ - ULB,
Brussels, Belgium.
6. February 15, 2007: Thomas Hertog, “Holographic
Cosmology: A New Paradigm?”
- DAMTP, University of Cambridge, UK.
7. February 15-17, 2007: Riccardo Argurio,
“Dynamical Supersymmetry Breaking” - 21st
Nordic Network Meeting on “Strings, Fields
and Branes” - Nordita, Stockholm, Sweden.
8. February 21, 2007: Riccardo Argurio,
“Metastable Supersymmetry Breaking and
Gauge/Gravity Duality” - Chalmers University
of Technology, Sweden.
10. March 9, 2007: Riccardo Argurio,
“Metastable Supersymmetry Breaking and
Gauge/Gravity Duality” - Utrecht University,
the Netherlands.
11. March 15, 2007: Laurent Houart, “On
infinite Kac-Moody Symmetries in (super)
gravity” - Pontificia Universidad Catolica de
Chile, Santiago de Chile, Chile.
12. March 20, 2007: Laurent Houart,
“On infinite Kac-Moody Symmetries in (super)
gravity” - CECS, Valdivia, Chile.
13. April 14-18, 2007: Marc Henneaux,
“Algèbres de Kac-Moody Hyperboliques et
Applications à la Gravitation: une Introduction”
- School on “Noncommutative Geometry,
Field Theories and Quantum Gravity”
- Université d’Oran, Algeria.
14. April 16, 2007: Carlo Maccaferri, “Introduction
to Open String Field Theory”
- School on “Noncommutative Geometry,
Field Theories and Quantum Gravity” - Université
d’Oran, Algeria.
15. May 3, 2007: Alexander Sevrin, “Wandering
in Superspace” - YITP@40 - CNYITP
Stony Brook, New York, USA.
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Research on Gravitation, Strings & Cosmology
16. May 12-15, 2007: Marc Henneaux,
“Spacelike Singularities and Infinite-Dimensional
Algebras in Gravitation Theory” -
“Black Holes VI” - White Point, Nova Scotia,
Canada.
17. June 7, 2007: Thomas Hertog, “From Big
Crunch to Big Bang with AdS/CFT” - Department
of Physics, Imperial College, UK.
18. June 12, 2007: Riccardo Argurio,
“Metastable Supersymmetry Breaking and
Gauge/Gravity Duality” - Swansea University,
UK.
19. June 15, 2007: Thomas Hertog, “A Holographic
Big Bang” - Department of Physics,
Nottingham University, UK.
20. June 18-22, 2007: Laurent Houart, “An
E9 multiplet of BPS States” - Conference “Prestring
2007” - Universidad de Granada,
Spain.
21. July 9, 2007: Ben Craps, “A cosmological
singularity in AdS/CFT” - Workshop on
“Cosmology and Strings” - ICTP Trieste, Italy.
22. August 1-10, 2007: Glenn Barnich, “BV
cohomology, duality and thermodynamics
of black holes dyons” - Programme “Poisson
Sigma Models, Lie Algebroids, Deformations
and Higher Analogues” - ESI Institute,
Vienna, Austria.
23. August 6 -10, 2007: Marc Henneaux,
“Selected applications on the antifield-BRST
(BV) formalism” - Course at ESI Institute,
Vienna, Austria.
24. August 26-31, 2007: Laurent Houart,
“An E9 in E11 multiplet of BPS states” -
Conference “International Conference on
Symmetries of String Theory” - Centro Stefano
Franscini, Ascona, Italy.
25. August 27, 2007: Marc Henneaux,
“Hidden Symmetries in Gravity” - CECS,
Valdivia, Chile.
26. September 17-22, 2007: Glenn Barnich,
“Dyons with Potentials: Duality and Black
Hole Thermodynamics” - Fourth Aegean Summer
School, Mytilene, Greece.
27. October 1, 2007: Carlo Maccaferri,
“Presentation of the Brussels Theoretical
Physics Group” - 3rd RTN Workshop
“Constituents, Fundamental Forces and Symmetries
of the Universe” – Valencia, Spain.
28. October 2, 2007: Carlo Maccaferri,
“New Vortices in Noncommutative Gauge
Theories” - 3rd RTN Workshop “Constituents,
Fundamental Forces and Symmetries of the
Universe” - Valencia, Spain.
29. October 2, 2007: Oleg Evnin, “Quantum
evolution across singularities” - 3rd RTN
Workshop - Valencia, Spain.
30. October 17-23, 2007: Glenn Barnich,
“Algebraic structure of gauge systems: theory
and applications” - ESF Conference “Algebraic
aspects in Geometry” - Mathematical
Research and Conference Center, Bedlewo,
Poland.
130

Research on Gravitation, Strings & Cosmology
31. October 22, 2007: Carlo Maccaferri,
“Introduction to the Bosonic String” - Doctoral
school Amsterdam-Brussels-Paris, Brussels,
Belgium.
32. October 23-31, 2007: Ben Craps,
“D-branes” - Amsterdam-Brussels-Paris Doctoral
school on theoretical physics, Brussels,
Belgium.
33. October 25, 2007: Marc Henneaux,
“De l’utilité de la connaissance ‘inutile’ “
– Maison de la Laïcité Condorcet - Belgium.
34. October 29-30, 2007: Carlo Maccaferri,
“Basics of Open String Field Theory”
- Amsterdam-Brussels-Paris Doctoral school
on theoretical physics, Brussels, Belgium.
36. November 26, 2007: Mohab Abou
Zeid, “Physics at the LHC and beyond” - UAE-
CERN Workshop - Al Ain, United Arab Emirates.
37. December 11, 2007: Francesco Bigazzi,
“Five Dimensional String Theory and QCD”
- University of Wales, Swansea, UK.
38. December 19, 2007: Thomas Hertog,
“AdS/CFT Dual Description of Cosmological
Singularities” - Conference “The Very Early
Universe, 25 years on” - Centre for Theoretical
Cosmology, DAMTP, University of Cambridge,
UK.
35. November 8, 2007: Riccardo Argurio,
“Metastable Supersymmetry Breaking and
Gauge/Gravity Duality” - Niels Bohr Institutet,
Copenhagen, Denmark.
131

Research on Gravitation, Strings & Cosmology
Publications 2007
1. M. Abou Zeid - Twistor Strings and Supergravity
- in the proceedings of the Cairo
International Conference on High Energy
Physics II, German University in Cairo, Egypt,
American Institute of Physics Press, Conference
Proceedings 881 48-57 (2007).
2. M. Abou Zeid - Twistor Strings and
Supergravity - Fortsch. Phys.55 621-626
(2007).
3. A. Amsel, T. Hertog, S. Hollands, D. Marolf
- A Tale of Two Superpotentials: Stability
and Instability in Designer Gravity - Phys.
Rev. D75 (2007) 084008.
4. R. Argurio, M. Bertolini, S. Franco,
S. Kachru - Gauge/Gravity Duality and
Meta-stable Dynamical Supersymmetry
Breaking - JHEP 0701:083, 2007 - [e-Print
Archive: hep-th/0610212].
5. R. Argurio, M. Bertolini, S. Franco,
S. Kachru - Metastable Vacua and D-branes
at the Conifold - JHEP 0706:017, 2007 - [e-
Print Archive: hep-th/0703236].
6. R. Argurio, M. Bertolini, G. Ferretti,
A. Lerda, C. Petersson - Stringy Instantons
at Orbifold Singularities - JHEP 0706:067,
2007 - [e-Print Archive: 0704.0262].
7. R. Argurio, C. Closset - A Quiver of Many
Runaways - JHEP 0709:080, 2007 - [e-Print
Archive: 0706.3991].
8. R. Argurio, C. Closset, M. Bertolini, S. Cremonesi
- Stable non-Supersymmetric Vacua
at the Bottom of Cascading Gauge Theories
- Fortsch. Phys. 55:555-560, 2007.
9. R. Argurio, M. Bertolini, S. Franco,
S. Kachru - Metastable Supersymmetry
Breaking and Gauge/Gravity Duality -
Fortsch. Phys. 55:644-648, 2007.
10. G. Barnich, G. Compère - Classical Central
Extension for Asymptotic Symmetries
at Null Infinity in Three Spacetime Dimensions
- Class. Quant. Grav.24:F15, 2007,
Erratum-ibid. 24:3139, 2007 - [e-Print Archive:
gr-qc/0610130].
11. G. Bertoldi, F. Bigazzi, A.L. Cotrone,
J. Edelstein - Holography and unquenched
quark-gluon plasmas - Phys. Rev.
D76:065007, 2007 - [e-Print Archive: hepth/0702225].
12. F. Bigazzi, A.L. Cotrone, L. Martucci,
W. Troost - Splitting of macroscopic fundamental
strings in flat space and holographic
hadron decays - Mod. Phys. Lett.
A22: 1057-1074, 2007 - [e-Print Achive:
hep-th/0703284].
13. L. Bonora, C. Maccaferri, R.J. Scherer Santos,
D.D. Tolla - Ghost story. I. Wedge states in
the oscillator formalism - JHEP 0709:061,
2007 - [e-Print Archive: 0706.1025].
14. N. Bouatta, J. Evslin, C. Maccaferri -
Puffed Noncommutative Nonabelian
Vortices - JHEP 0704:037, 2007 - [e-Print
Archive : hep-th/0702042].
132

Research on Gravitation, Strings & Cosmology
15. C. Bunster, M. Henneaux - A Monopole
Near a Black Hole - PNAS (USA) 104:
12243-12249, 2007 - [e-Print Archive: hepth/0703155].
16. A. Collunici, J. Evslin - Twisted Homology
- JHEP 0703:058, 2007 - [e-Print Archive:
hep-th/0611218].
17. G. Compère - A note on the first law
with p-form potentials - Phys. Rev.
D75: 124020, 2007 - [e-Print Archive:
hep-th/0703004].
18. G. Compère, S. Detournay - Centrally
extended symmetry algebra of asymptotically
Goedel spacetimes - JHEP 03:098,
2007 - [e-Print Archive: hep-th/0701039].
19. B. Craps, O. Evnin, S. Nakamura
- Local recoil of extended solitons: A
String theory example - Published in JHEP
0701:050,2007.
20. S. Deser, M. Henneaux - A Note on
Spin Two Fields in Curved Backgrounds -
Class. Quant. Grav. 24: 1683-1686, 2007 -
[e-Print Archive: gr-qc/0611157].
21. F. Englert, L. Houart, A. Kleinschmidt, H.
Nicolai, N. Tabti - An E(9) multiplet of BPS
states - JHEP 0705:065, 2007 - [e-Print
Archive: hep-th/0703285].
22. M. Eto, J. Evslin, K. Konishi, G. Marmorini,
M. Nitta, K. Ohashi, W. Vinci, N. Yokoi - On
the Moduli Space of Semilocal Strings
and Lumps - Phys. Rev. D76: 105002, 2007
- [e-Print Archive: 0704.2218].
23. J. Evslin, S. Kuperstein - Trivializing and
Orbifolding the Conifold’s Base - JHEP
0704:001, 2007 - [e-Print Archive: hepth/0702041].
24. J. Evslin, L. Martucci - D-Brane Networks
in Flux Vacua, Generalized Cycle and
Calibrations - JHEP 0707:040, 2007 - [e-
Print Archive: hep-th/0703129].
25. J. Evlin, C Krishnan, S. Kuperstein - Cascading
Quivers from Decaying D-Branes
- JHEP 0708:020, 2007 - [e-Print Archive:
0704.3484].
26. F. Ferrari - The Chiral ring and the periods
of the resolvent - Nucl. Phys. B770:
371-383, 2007 - [e-Print Archive: hepth/0701220].
27. F. Ferrari - Microscopic quantum superpotential
in N=1 gauge theories
- JHEP 0710:065, 2007 - [e-Print Archive:
0707.3885].
28. F. Ferrari - Extended N=1 Super Yang-
Mills Theory - JHEP 0711:001, 2007 -
[e-Print Archive: 0709.0472].
29. F. Ferrari, S. Kuperstein, V. Wens - Glueball
operators and the microscopic approach
to N=1 gauge theories - JHEP 0710:101,
2007 - [e-Print Archive: 0708.1410].
30. W. Fischler, V. Kaplunovsky, C. Krishnan,
L. Mannelli, M. Torres - Meta-Stable Supersymmetry
Breaking in a Cooling Universe
- JHEP 0703:107, 2007- [e-Print Archive:
hep-th/0611018].
133

Research on Gravitation, Strings & Cosmology
31. M. Henneaux, M. Leston, D. Persson,
P. Spindel - A Special Class of Rank
10 and 11 Coxeter Groups - J. Math.
Phys. 48:053512, 2007 - [e-Print Archive:
hep-th/0610278].
32. M. Henneaux, C. Martinez, R. Troncoso,
J. Zanelli - Asymptotic Behavior and Hamiltonian
Analysis of Anti-de Sitter Gravity
coupled to Scalar Fields - Annals Phys.
322: 824-848, 2007 - [e-Print Archive: hepth/0603185].
33. T. Hertog - Holographic Cosmology -
in “Particle Physics and Cosmology: the
Fabric of Spacetime” - Eds F. Bernardeau,
C. Grojean, J. Dalibard, Elsevier (2007).
34. T. Hertog - Violation of Energy Bounds
in Designer Gravity - Class. Quant. Grav. 24
(2007).
35. C. Krishnan, E. Di Napoli - Can Quantum
de Sitter Space Have Finite Entropy?
- Class. Quant. Grav. 24: 3457-3463, 2007
- [e-Print Archive: hep-th/0602002].
36. A. Sevrin, W. Staessens, A. Wijns - The
World-sheet description of A and B
branes revisited - Published in JHEP 0711
(2007) 061.
37. N. Tabti - Gravitational theories coupled
to matter as invariant theories under
Kac-Moody algebras - Fortsch. Phys.55:
821-826, 2007 - [e-Print Archive: hepth/0701165].
38. C. Troessaert - Fractions continues et
actions des groupes de congruence sur
la droite réelle - Bull. Belg. Math. Soc. Simon
Stevin 14, 4, 669-680, 2007.
39. A. Wijns - D-brane effective action and
boundary superspace - Nucl. Phys. Proc.
Suppl. 171:334-336 (2007).
Preprints
40. M. Abou Zeid - Twistor Strings, Gauge
Theory and Gravity - to appear in the proceedings
of the UAE-CERN Workshop Physics
at LHC and Beyond - Al Ain, United Arab
Emirates, American Institute of Physics Press,
Conference Proceedings (2008).
41. M.Abou Zeid - Symmetries, Conservation
Laws and Gauge Invariant Operators
in Noncommutative Field Theory -
to appear in the proceedings of the 21st
Nishionomiya-Yukawa Memorial Symposium
Noncommutative geometry and quantum
spacetime in physics - Progress of Theoretical
Physics Supplement (2007).
42. M. Abou Zeid, C.M. Hull and L.J. Mason
- Einstein Supergravity and New Twistor
String Theories - [arXiv: hep-th/0606272],
accepted for publication in Communications
in Mathematical Physics (2008).
43. L. Bao, J. Bielecki, M. Cederwall, B. Nilsson,
D. Persson - U-Duality and the Compactified
Gauss-Bonnet Term - e-Print Archive:
0710.4907.
134

Research on Gravitation, Strings & Cosmology
44. G. Barnich, A. Gomberoff - Dyons with
Potentials: Duality and Black Hole Thermodynamics
- e-Print Archive: 0705.0632.
45. G. Barnich, G. Compère - Surface
Charge Algebras in Gauge Theories and
Thermodynamic Integrability - e-Print Archive:
0708.2378.
46. B. Craps, O. Evnin - Quantum evolution
across singularities - e-Print: arXiv:
0706.0824[hep-th].
47. B. Craps, T. Hertog, N. Turok - Quantum
Resolution of Cosmological Singularities
using AdS/CFT - e-Print: arXiv: 0712.4180
[hep-th].
48. G. Compère - Symmetries and conservation
laws in Lagrangian gauge theories
with applications to the mechanics of
black holes and to gravity in three dimensions
- e-Print Archive: 0708.3153.
49. J. Evslin, C. Krishnan - The Black Di-ring:
An Inverse Scattering Construction - e-Print
Archive: arXiv:0706.1231.
50. F. Ferrari, V. Wens - Consistency conditions
in the chiral ring of super Yang-Mills
theories - e-Print Archive: 0710.2978.
51. W. Fischler, C. Krishnan, S. Paban, M.
Zanic - Vacuum Bubble in an Inhomogeneous
Cosmology: a Toy Model - e-Print
Archive: arXiv: 0711.3417.
52. J.B. Hartle, S.W. Hawking, T. Hertog - The
No-Boundary Measure of the Universe -
[arXiv: 0711.4630[hep-th]].
53. M. Henneaux, D. Persson, P. Spindel
- Spacelike Singularities and Hidden
Symmetries of Gravity - e-Print Archive:
arXiv:0710.1818.
54. E. Jamsin - A Note on conserved charges
of asymptotically flat and anti-de Sitter
spaces in arbitrary dimensions - e-Print
Archive: 0705.0484.
55. N. Turok, B. Craps, T. Hertog - From big
crunch to big bang with AdS/CFT - e-Print:
arXiv: 0711.1824 [hep-th].
Edition
Proceedings Henri Poincaré - P. Gaspard, M.
Henneaux, F. Lambert eds, Proceedings of
the Solvay Workshops and Symposia (n° 2)
(199 pages).
The Quantum Structure of Space and Time - D.
Gross, M. Henneaux, A. Sevrin eds, Proceedings
of the 23rd Solvay Conference on Physics
- World Scientific Publishing Co (2007).
135

136

Sponsored by the Institutes
RESEARCH CARRIED OUT
IN THE GROUP OF THE
DEPUTY DIRECTOR
137

Research carried out in
Members
Permanent Members
Franklin Lambert (VUB)
Micheline Musette (VUB)
Postdoctoral Members
Thomas Durt (FWO, VUB)
Ignace Loris (FWO VUB, Francqui ULB)
Zsislaw Suchanecki (Université du Luxembourg)
Caroline Verhoeven (FWO VUB)
Alexandre Volkov (Solvay Institutes, VUB)
Ralph Willox (University of Tokyo)
Doctoral Members
Fred Vanden Berghe (VUB)
138

the Group of the Deputy Director
Research Summary
Nonlinear dynamics, solitons and
integrability
The group has a long standing research activity
on nonlinear wave equations, and more
specifically on integrable or nearly integrable
ones. Integrable or solvable models are
usually not suited to represent a physical situation
in full detail. Yet, they constitute the
mathematical core and starting point from
which realistic models can be approximated.
Nonlinear integrable systems are also found
to show up in the context of many important
and different problems. Their study, in both
the classical and the quantum domain, has
therefore become a corner stone of modern
mathematical physics.
Our research, which was carried out in 2007
on this matter, and the results that have been
obtained can be summarized as follows:
° Extension of a previously developed algorithmic
method for the systematic construction
of members of infinite integrable families (hierarchies)
of classical soliton equations. This
procedure now leads to a natural gradation
of the Hirota equations of a given weight that
make up the bilinear KP and modified KP hierarchies.
The work was done in collaboration
with R. Willox of the University of Tokyo.
° Completion of “The Painlevé handbook”,
by R. Conte and M. Musette. The purpose of
this book is to present a comprehensive introduction
to nonperturbative methods – in particular
the algorithm, called the Painlevé test
– allowing one to build explicit solutions to
nonlinear differential or difference equations.
This book is a final and lasting result of a long
and successful collaboration with CE Saclay
(Service de Physique de l’état condensé,
CNRS URA 2464).
° Continuation of our investigation of possible
soliton instabilities in 2+1 dimensional
integrable models, that may lead to complex
interaction patterns, described by s.c. “spiderweb”
solutions. We examined the behaviour
of dromion solutions in the KP context, and
showed that the localized character of such
solutions can survive under particular resonance
conditions.
° Completion of the proof of Zamolodchikov’s
periodicity conjecture for Y-systems
in the milestone particular case A-A. Y-systems,
also known as thermodynamical Bethe
ansätz equations, are pivotal in the theory of
quantum integrable systems. The beauty of
the matter is that these equations, on the one
hand, describe a quantum statistical model
and, on the other hand, can be interpreted
as a classical lattice model, which happens
to be the ubiquitous Hirota or lattice KP equation.
Our study of Y-systems took place in the
framework of a collaboration with L. Faddeev
of St Petersburg’s Steklov Institute and R. Kashaev
of the University of Geneva.
Nonlinear equations
and inverse linear problems
Inverse scattering problems became popular
in soliton theory as a result of the discovery of
139

Research carried out in
a possibility of solving initial value problems
for integrable NLPDE’s by means of the inverse
scattering method. Inverse problems
are also known to be ill-posed. A new direction
in the group’s research originated in a
collaboration with I. Daubechies of Princeton
University and C. De Mol of ULB on the application
of sparse techniques for the solution
of ill-posed inverse linear problems. We studied
the effectiveness of sparsity promoting
penalties for regularizing ill-posed problems
for which we know the solution is sparse in
a certain basis. However, sparsity-promoting
penalties make the equations we want to solve
nonlinear. We therefore need to develop
fast reconstruction algorithms that can solve
the nonlinear equations. We started to work
in this direction, and have already tested the
basic principles of sparse reconstruction on
models in seismic tomography.
Fundamental aspects of quantum
and quantum information theory
We investigated the properties of kaons
(oscillations and CP violation) with the help
of the Friedrichs model. This approach provided
new insight in the phenomenology of
kaonic particles and in fundamental aspects
of quantum theory (formalism of the time superoperator
of Prigogine and co-workers).
We examined in detail the role of decoherence
and entanglement during the decay of
kaons, by reformulating the Friedrichs model
in the framework of tensorially factorizable
Hilbert spaces. Plans for a collaboration on
this subject with T. Izumi of the KEK Center in
Japan, were made during a visit of T. Durt at
Tsukuba. This collaboration should focus on
EPR-type flavour entanglement in semileptonic
B° decay.
140

1. January 11 - February 10, 2007: Ralph
Willox, invited lecturer at the Laboratoire
IMNC, Universités de Paris XII and Paris XI,
France.
2. March, 2007: Thomas Durt, invited
seminar “Applications of the generalized
Pauli group in Quantum Information” - KEK,
Japanese Center for High Energy Physics,
Tsukuba, Japan.
3. May 2007: Thomas Durt, contributing
seminar “Quantum Information, a Survey”
- Annual meeting of the Belgian Physical
Society, UIA, Antwerp, Belgium.
the Group of the Deputy Director
Invited Talks at Conferences,
Seminars and Schools
4. July 2007: Ralph Willox, contributing
paper “Local Darboux transformations and
geometric crystals” - ISLAND 3 Conference
on Algebraic Aspects of Integrable systems,
Islay, Scotland, UK.
5. December 2007: Thomas Durt, participation
to the IEEE/LEOS Symposium Benelux
Chapter. Poster on “Symmetric Informationally
Complete POVM tomography: theory
and applications”, Belgium.
6. December 2007: Thomas Durt, invited
seminar “Are biophotons quantum coherent
quantum systems?” - International Institute of
Biophysics, Neuss, Germany.
141

Research carried out in
Publications 2007
1. M. Courbage, T. Durt and S.M. Saberi Fathi
- Two level Friedrichs model and kaonic
phenomenology - Phys. Lett. A 362 (2007),
100-104.
2. M. Courbage, T. Durt and S.M. Saberi
Fathi - Quantum mechanical decay laws
in the neutral kaons - J. Phys. A 40 (2007),
2773-2785.
3. T. Durt - Symmetric Informationally Complete
POVM tomography: theory and applications
- 2007 IEEE/LEOS Symposium
Benelux Chapter Proceedings, 215-219.
4.. T. Durt - Quantum Information, a Survey
- Physicalia Mag. 29, 4 (2007), 145-160.
5. B. Grammaticos, A. Ramani, V. Papageorgiu,
J. Satsuma and R. Willox - Constructing
lump-like solutions of the Hirota-Miwa
equation - J. Phys. A 40 (2007), 12619-
12627.
6. C. King, F. Melakessou, V. Sorger and
Z. Suchanecki - Route diversity: future of
transmission protocols - Proceedings of the
IV th Int. Conference BROADNETS, Raleigh,
North Carolina (2007).
7. F. Lambert, J. Springael, S. Colin and R.
Willox - An elementary approach to hierarchies
of soliton equations - J. Phys. Soc.
Japan, vol 76, 5 (2007), 54005-54015.
8. I. Loris, G. Nolet, I. Daubechies and F.A.
Dalhen - Tomographic inversion using l1
norm regularization of wavelet coefficients
- Geophysical Journ. Int. 170 (2007),
359-370.
9. F. Melakessou, V. Sorger and Z. Suchanecki
- On the road towards the comprehension
of the internet traffic behaviour - Simulation
series, vol 39, 2 (2007), 193-202.
10. A. Volkov - On the periodicity conjecture
for Y-systems - Comm. Math. Phys. 276
(2007), 509-517.
11. R. Willox, A. Ramani, J. Satsuma and B.
Grammaticos - From limit cycles to periodic
orbits through ultradiscretization - Physica
A, 385 (2007), 473-486.
12. R. Willox, F. Lambert and J. Springael
- From canonical binilear forms to bi-Hamiltonian
structures - (in Japanese) Proceedings
of the RIAM Symposium 18 ME- S 5,
Research Inst. in Appl. Mech., University of
Kyushu (2007), art. 8.
142

the Group of the Deputy Director
Preprints
13. J. Corbett and T. Durt - Quantum
mechanics interpreted in quantum real
numbers - to appear in Studies in History
and Philosophy of Modern Physics.
Edition
R. Conte and M. Musette
The Painlevé handbook - Monograph,
Springer (2008)
14. M. Courbage, T. Durt and S.M. Saberi
Fathi - Quantum Hamiltonian Dynamics of
kaons phenomenology - Special issue of
Communications in Nonlinear Science and
Numerical Simulation (in press).
15. I. Daubechies, M. Formasier and I. Loris
- Accelerated projected gradient method
for linear inverse problems with sparsity
constraints - to appear in J. Fourier Anal. and
Appl.
16. T. Durt, C. Kurtsiefer, A. Lamas-Linares
and A. Ling - Wigner tomography of two
qubit states and quantum cryptography -
to appear in Phys. Rev. A.
17. T. Durt, D. Kaslikowski and L.C. Kwek -
Generalized flying qudit scheme in arbitrary
dimensions - to appear in Phys. Rev. A.
18. A.N.W. Hone, V. Novikov and C. Verhoeven
- An extended Hénon-Heiles system
- to appear in Phys. Lett. A.
19. F. Lambert and J. Springael - Soliton
equations and simple combinatories - to
appear in Acta Appl. Math.
143

144

Sponsored by the Institutes
Appendix: Outreach
Newspapers & Radio Interviews
and Edition
145

Radio Interviews and Edition
Radio Interview
Alexandre Sevrin
May 21, 2007
Radio 1 VRT: “de Wandelgangen” at the occasion of the Solvay
Public Event with Stephen Hawking and Harold Kroto
Edition
Symposium Henri Poincaré
Proceedings
P. Gaspard, M. Henneaux, F. Lambert eds
Solvay Workshops and Symposia - Volume 2
(199 pages)
146

Newspapers
Newspapers
January 2007 – Brussels Expo News, Programme 2007, Belgium
March 27, 2007 – Metro (p.5), Belgium
March 30, 2007 – De Standaard (p. L5), Belgium
March 30, 2007 – Le Soir (p.17), Belgium
April 3, 2007 – La Libre Belgique (p.17), Belgium
April 4, 2007 – La Libre en ligne, Belgium
May 4, 2007 – La Libre Belgique (Lire VI), Belgium
May 18, 2007 – Le Vif/l’Express (p.39), Belgium
May 18, 2007 – Het Nieuwsblad on line, Belgium
May 18, 2007 – De Standaard on line, Belgium
May 19-20, 2007 – Le Soir (p.17), Belgium
May 19-20, 2007 – La Libre Belgique (p.41), Belgium
May 21, 2007 – Le Soir, Belgium
October 23, 2007 – Le Soir, Belgium
November 2007 – WB Magazine N° 9/2007 (p.20), Belgium
November 27, 2007 – La Libre Belgique (p.28-29), Belgium
December 26, 2007 – El Pais (p.39), Spain
January 2008 – La Recherche (p. 12), France
January 3, 2008 – Knack (p.48), Belgium
147

Newspapers
January 2007 – Brussels Expo News, Programme 2007, Belgium
148

Newspapers
March 27, 2007 – Metro (p.5), Belgium
149

Newspapers
March 30, 2007 – De Standaard (p. L5), Belgium
150

Newspapers
March 30, 2007 – Le Soir (p.17), Belgium
151

Newspapers
April 3, 2007 – La Libre Belgique (p.17), Belgium
April 4, 2007 – La Libre en ligne, Belgium
152

Newspapers
May 4, 2007 – La Libre Belgique (Lire VI), Belgium
153

Newspapers
May 18, 2007 – Le Vif/l’Express (p.39), Belgium
154

Newspapers
155

Newspapers
May 18, 2007 – Het Nieuwsblad on line, Belgium
May 18, 2007 – De Standaard on line, Belgium
156

Newspapers
May 19-20, 2007 – Le Soir (p.17), Belgium
157

May 19-20, 2007 – La Libre Belgique (p.41), Belgium
Newspapers

Newspapers

Newspapers
May 21, 2007 – Le Soir, Belgium
October 23, 2007 – Le Soir, Belgium
160

Newspapers
November 2007 – WB Magazine N° 9/2007 (p.20), Belgium
161

November 27, 2007 – La Libre Belgique (p 28-29), Belgium
Newspapers
November 27, 2007 – La Libre Belgique (p.28), Belgium
162

Newspapers
163

Newspapers
December 26, 2007 – El Pais (p.39), Spain
164

Newspapers
January 2008 – La Recherche (p. 12), France
165

Newspapers
January 3, 2008 – Knack (p.48), Belgium 166

Newspapers
167

Newspapers
January 3, 2008 – Knack (p.48), Belgium 168