ENRICO TASSI - Zeus - Desy

OCTOBER 2008
ENRICO TASSI
Curriculum Vitae
Contact Address:
At CERN:
Office: 40-2-C12
Università della Calabria
CERN CH-1211 - Geneva 23 - Switzerland.
Dipartimento di Fisica
tel: +41-22-76-71147 - email: Enrico.Tassi@cern.ch
Via P. Bucci, Cubo 31C
87036 Arcavacata di Rende (CS) - Italy At DESY:
tel: +39-0984-49-6038 Office: Bld. 1c/290
fax: +39-0984-49-4401
Notkestrasse 85 - 22607 Hamburg - Germany
email: tassi@fis.unical.it
tel: +49-40-8998-2716 - email: tassi@mail.desy.de
CURRENT ACADEMIC POSITION
Associate Professor (2005-present)
Physics Department, Università della Calabria.
PAST POSITIONS
Visiting Professor (2004-2005)
Physics Department, Università della Calabria.
Visiting Professor (2003-2004)
Physics Department, Universidad Autonoma de Madrid - Spain.
Research Assistant (2001-2003)
NIKHEF Laboratory, Amsterdam - The Netherlands.
EDUCATION
Ph.D., 2001
Laurea, 1994
Universität Hamburg.
Dissertation: Measurement of dijet production in neutral current deep inelastic
scattering at high-Q 2 and determination of α s at HERA
Università degli studi di Roma “La Sapienza”.
Thesis: Study of the production of charmed mesons at HERA
FELLOWSHIPS
“Ramon y Cajal” Research Fellowship - 2002-2007
Five years Research Fellowship programme launched in 2001 by the spanish government to incorporate
young scientists into the spanish centres for research and universities.
“Rientro dei Cervelli” Research Fellowship - 2004-2007
Three years Research Fellowship programme launched by the italian government in order to facilitate the
return from abroad of italian scholars and scientists.
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TEACHING
Courses
Electromagnetism and Optics - Academic years 2002-2003 and 2003-2004.
Three months course for second year chemistry students (in spanish).
Faculty of Science. Universidad Autonoma de Madrid, Spain.
Mechanics and Thermodynamics - Since the academic year 2004-2005.
Three months course delivered to first year students of the Faculty of Science.
Università della Calabria.
Electromagnetism - Since the academic year 2005-2006.
Three months course delivered to second year physics students.
Università della Calabria.
Nuclear and Subnuclear Physics - Since the academic year 2004-2005.
Three months course delivered to forth year physics students.
Università della Calabria.
Data analysis and Montecarlo techniques in HEP - Since the academic year 2004-2005.
24 hours course delivered to Ph.D students.
Università della Calabria.
Schools
2003 CTEQ Summer School
2006 XXXIV International Meeting on Fundamental Physics
Academic Supervision
Starting from the academic year 2005-2006 I have supervised the following students:
Antonia Morabito - 3rd year Physics Degree - (ATLAS Experiment: Z 0 production)
Valerio Scarfone - 3rd year Physics Degree - (ATLAS Experiment: W ± production)
Vincenzo Lavorini - 5th year Physics Degree - (ATLAS Experiment: Top production)
and will supervise two others third year students in the forthcoming academic year. I also supervised
numerous students whilst convener of the “Structure Functions” working group of the ZEUS experiment.
RESEARCH ACTIVITY
A member of the ZEUS Experiment at HERA since 1995 and of the ATLAS Experiment at the LHC since
2002 with more than 170 publications in international journals with an average of 50 citations per paper.
Physics Highlights
1. Measurements of jet cross sections in neutral current (NC) Deep Inelatic Scattering (DIS) [1–6].
The study of dijet production in NC DIS, which I performed as part of my Ph.D. work, was the
first analysis at HERA to demonstrate the possibility to measure jet cross sections in DIS with
high experimental accuracy. This allowed stringest tests of pQCD to be performed for the first
time as well as the first determination of the strong coupling constant, α s , from jet cross sections at
HERA. The techniques developed for this analysis (jet energy scale, tuning of the MC samples, NLO
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predictions and extraction of α s ) have since then been used in subsequent ZEUS jet cross sections
measurements, to which I have substantially contributed, and rank among the most accurate in the
world.
2. Measurements of the inclusive cross sections in neutral current and charged current (CC) DIS with
polarised and unpolarised lepton beams [7–13].
During the seven years of my tenure (2001-2007) as convener of the ZEUS “Structure Functions”
working group I took responsibility for bringing to completion most of the ZEUS measurements of
the NC and CC DIS inclusive cross sections at low, medium and high Q 2 . As well known these
measurements are of utmost importance in the determination of the proton PDFs, in particular
the sea and gluon densities at low and medium x. The inclusive cross sections at high-Q 2 , in
addition to provide information on the valence-quark densities, give a wonderful demonstration of
the unification of the electromagnetic and weak interactions at the electroweak scale. Another physics
highlight during my coordination period was the first measurement at ZEUS of the DIS cross section
with polarised positrons. This measurement was particularly important not only because provided
comfirmation of the chiral structure of the weak force in the Standard Model but also because
was the first paper published by ZEUS after the accelerator (HERA II) and detector upgrade. It
was hence necessary to perform detailed studies to re-calibrate the ZEUS detector and re-optimise
reconstruction algorithms.
3. NLO DGLAP QCD analysis of inclusive and exclusive HERA data and determination of the proton
parton distribution functions (PDFs) [14, 15].
While working as convener of the ZEUS “Structure Functions” working group I was also strongly
involved in the DGLAP analyses of inclusive and semi-exclusive (jet) cross sections at HERA and in
the determination of the proton PDFs. In particular I developed a method to include in a rigorous
way (i.e. without the use of the so-called K factors) the jet cross sections, both in the DIS and the
photoproduction regimes, in the DGLAP fitting programs. The inclusion of the jet cross sections
in the DGLAP analysis, in addition to provide a confirmation of the factorization theorem of QCD,
has resulted in a significant reduction of the uncertainty affecting the gluon density as well as in
a one of the most precise determination of the strong coupling constant to date. I developed a
similar approach also for the inclusion of the charm and bottom visible cross sections in the DGLAP
analysis but presently, due to the limited statistical precision of the meaurements, these observables
have had a minor impact on the determination of the PDFs.
4. Combination of the measurements of the H1 and ZEUS collaborations [16, 17].
In 2006 I was appointed convener of the “HERA Structure Function Working Group”. This group
was created by the H1 and ZEUS collaborations with the specific goal to a) develop methods for
the combination of the NC and CC inclusive cross sections measured by the two experiments and
based on a joint data sample amounting to almost 1 fb −1 and b) perform a new determination of
the PDFs based on a DGLAP analysis of the combined data sets. In less than two years the working
group has produced impressive results: at the 2007 Lepton-Photon symposium we submitted a paper
that demostrated how the combination of the H1 and ZEUS measurements could produce sensible
reductions (in some cases up to factors three or four) of the original systematic uncertainties quoted
by the experiments and this year we released at the ICHEP 2008 conference the first preliminary
PDFs extracted from the combined cross sections and characterised by a much improved precision
compared to the present global fits.
5. Phenomenological studies of the impact of the HERA measurements and PDFs in the physics program
of the LHC.
Recently my activity has been devoted to perform phenomenological studies aimed at assessing the
impact of the PDFs, recently measured at HERA, on the physics program at the LHC. Specifically
I’m studying the impact of the HERA PDFs on the theoretical uncertainty of the W ± and Z 0 bosons
production cross sections at the LHC. These processes will play a crucial role in the calibration of
the ATLAS and CMS detectors in the early phase of data taking and can be used for a precise
determination of the luminosity provided the theoretical uncertainty (dominated by the PDFs) can
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e kept at the few percent level. With the goal of testing the universality of the PDFs, I’m also
producing predictions for the jet cross sections at the Tevatron and the LHC based on the latest
HERA PDFs that have been extracted using HERA data only.
Software/Hardware Work
1. Object Oriented Tag Database [18]
As a technical part of my Ph.D. work I developed, and integrated into the ZEUS analysis framework,
an object oriented tag database for a flexible and fast selection of interesting physics events. The
system (Zeus Event Store) has been since then routinely used in the ZEUS physics analyses.
2. ATLAS End-Cup Electromagnetic Calorimeter
While a member of the ATLAS-Madrid group I participated to the assembly, mechanical and electrical
tests of one of the two End-Cap liquid-Argon Electromagnetic calorimeters of the ATLAS
detector.
Appointments
- Coordinator of the Global Second Level Trigger of the ZEUS Experiment (2000-2002).
- Coordinator of the “Structure Functions and Beyond the Standard Model” working group of the
ZEUS Experiment (2001-2007).
- Convener and ZEUS contact person of the “HERA Structure Functions Working Group” (2006 -
present).
- I have been appointed ZEUS Physics Co-Chairman for the year 2009.
CONFERENCE TALKS/CONVENER
E. Tassi, [On behalf of the H1 and ZEUS Collaborations], “Electroweak Physics Measurements at HERA”,
Les rencontres de Physique de la Vallé d’Aoste, La Thuile, Aosta Valley, Italy (February 2008).
E. Tassi,“Electroweak Physics at HERA”, seminar at the XXXIV International Meeting on Fundamental
Physics, El Escorial, Madrid, Spain (April 2006).
E. Tassi, [On behalf of the ZEUS Collaboration], “Parton Distributions Functions and Jet Cross Sections
at HERA”, XXXIII International Conference on High Energy Physics (ICHEP06), Moscow, Russia
(July 2006).
E. Tassi, [On behalf of the ZEUS Collaboration], “NLO QCD Analysis of Inclusive and Jet Data from
ZEUS”, Workshop on Deep Inelastic Scattering, Diffraction and Related Matters (Low-x 2005), Sinaia,
Romania (June 2005).
E. Tassi, “Stato di ZEUS”, INFN - Commissione Scientifica Nazionale 1, Naples, Italy (September 2005).
Convener of the “Structure Functions and Low-x” working group at the XII International Workshop on
Deep Inelastic Scattering (DIS04), Strbské Pleso, Slovakia (April 2004).
E. Tassi, “An Experimental Introduction to Deep Inelastic Scattering”, Lectures at the 2003 CTEQ Summer
School, Sant Feliu de Guixols, Catalonia, Spain (May 2003).
E. Tassi, [On behalf of the H1 and ZEUS Collaborations], “Measurements of F 2 and F L at Low-Q 2 in e-p
Interactions at HERA”, Workshop on Small-x and Diffractive Physics, Fermilab, USA (September 2003).
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E. Tassi, [On behalf of the ZEUS Collaboration], “A ZEUS NLO QCD Analysis of Data on Deep Inelastic
Scattering”, X International Workshop on Deep Inelastic Scattering (DIS02), Cracow, Poland,
(April 2002).
E. Tassi, [On behalf of the ZEUS Collaboration], “ZEUS Status”, 54th DESY Physics Research Committe
(PRC), Hamburg, Germany (October 2002).
E. Tassi, [On behalf of the ZEUS Collaboration], “Jet Production in NC DIS and Determination of α s ”,
IX International Workshop on Deep Inelastic Scattering (DIS01), Bologna, Italy (April 2001).
E. Tassi, [On behalf of the H1 and ZEUS Collaborations], “The Strong Coupling and the Gluon Density
from Jet Production in DIS at HERA”, XXX International Conference on High Energy Physics
(ICHEP00), Osaka, Japan (July 2000).
E. Tassi, [On behalf of the ZEUS Collaboration], “The Strong Coupling from Dijet production in DIS at
HERA”, VII International Workshop on Deep Inelastic Scattering and QCD (DIS99), Zeuthen, Germany
(April 1999).
E. Tassi, “Inclusive Jet Cross Sections at High-Q 2 in Deep Inelastic Scattering at HERA”, Presented at
the 1998 Meeting of the German Physical Society, Freiburg, Germany (March 1998).
E. Tassi, [On behalf of the ZEUS Collaboration], “An ODBMS-Based Event Store for the Zeus Experiment”,
International Conference on Computing in High Energy Physics (CHEP), Berlin, Germany
(April 1997).
E. Tassi, “An ODBMS-Based Event Store for the ZEUS Experiment”, Presented at the RD45/Objectivity
Workshop, Geneva, Switzerland (March 1997).
LIST OF SELECTED PUBLICATIONS
[1] ZEUS Coll., J. Breitweg et al., “Measurement of dijet production in neutral current deep inelastic
scattering at high Q 2 and determination of α s ”, Phys. Lett. B 507 (2001) 70-88;
[2] ZEUS Coll., S. Chekanov et al., “Dijet production in neutral current deep inelastic scattering at
HERA”, Eur. Phys. J. C 23 (2002) 1, pp 13-27;
[3] ZEUS Coll., S. Chekanov et al., “Inclusive jet cross sections in the Breit frame in neutral current
deep inelastic scattering at HERA and determination of α s ”, Phys. Lett. B 547 (2002) 164-180;
[4] ZEUS Coll., S. Chekanov et al., “Study of the azimuthal asymmetry of jets in neutral current deep
inelastic scattering at HERA”, Phys. Lett. B 551 (2003) 226-240;
[5] ZEUS Coll., S. Chekanov et al., “Multijet Production in Neutral Current Deep Inelastic Scattering
at HERA and Determination of α s ”, Eur. Phys. J. C 44 (2005) 183-193;
[6] ZEUS Coll., S. Chekanov et al., “Inclusive jet and dijet cross sections in deep inelastic scattering at
HERA”, Nucl. Phys. B 765 (2007) 1-30;
[7] ZEUS Coll., S. Chekanov et al., “Measurement of the neutral current cross section and F 2 structure
function for deep inelastic e + p scattering at HERA”, Eur. Phys. J. C 21 (2001) 3, pp 443-471;
[8] ZEUS Coll., S. Chekanov et al., “Measurement of high-Q 2 charged current cross sections in e − p deep
inelastic scattering at HERA”, Phys. Lett. B 539(2002) 197-217, Erratum B 552 (2003) 308;
[9] ZEUS Coll., S. Chekanov et al., “Measurement of high-Q 2 e − p neutral current cross sections at HERA
and the extraction of x F 3 ”, Eur. Phys. J. C 28 (2003) 2, pp 175-201;
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[10] ZEUS Coll., S. Chekanov et al., “Measurement of high-Q 2 charged current cross sections in e + p deep
inelastic scattering at HERA”, Eur. Phys. J. C 32 (2003) 1-16;
[11] ZEUS Coll., S. Chekanov et al., “High-Q 2 neutral current cross section in e + p deep inelastic scattering
at √ s=318 GeV”, Phys. Rev. D 70 (2004) 052001;
[12] ZEUS Coll., S. Chekanov et al., “Measurement of High-Q 2 Deep Inelastic Scattering Cross Sections
with a Longitudinally Polarised Positron Beam at HERA”, Phys. Lett. B 637 (2006) 210-222;
[13] ZEUS Coll., S. Chekanov et al., “Measurement of Neutral Current Cross Sections at High Bjorken-x
with the ZEUS Detector at HERA”, Eur. Phys. J. C 49 (2007) 523-544;
[14] ZEUS Coll., S. Chekanov et al., “A ZEUS next-to-leading-order QCD analysis of data on deep inelastic
scattering”, Phys. Rev. D 67 (2003) 012007;
[15] ZEUS Coll., S. Chekanov et al., “An NLO QCD Analysis of Inclusive Cross-Section and Jet-
Production Data from the ZEUS Experiment”, Eur. Phys. J. C 42 (2005) 1-16;
[16] H1 and ZEUS Coll., “Combination of the H1 and ZEUS deep inelastic e ± p scattering cross sections
measurements”, contributed paper to the XXIII International Symposium on Lepton and Photon
Interaction at High Energy (LP2007), H1prel-07-007 and ZEUS-prel-07-026; avalilable at:
http://www-h1.desy.de/h1/www/publications/H1_sci_results.shtml;
[17] H1 and ZEUS Coll., “Extraction of the proton parton density functions using a NLO QCD fit of the
combined H1 and ZEUS inclusive DIS cross sections”, contributed paper to the XXXIV International
Conference on High Energy Physics (ICHEP2008), H1prel-08-045 and ZEUS-prel-003; available at:
http://www-h1.desy.de/h1/www/publications/H1_sci_results.shtml;
[18] L.A.T. Bauerdick, A. Fox-Murphy, T. Hass, S. Stoniek, E. Tassi, “ Event indexing systems for efficient
selection and analyis of HERA data”, Comp. Phys. Comm. 137 (2001) 236-246.
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