Georg G. Raffelt Max-Planck-Institut für Physik (München) - Fermilab

Georg G. Raffelt 

Max-Planck 

Max Planck-Institut Institut für Physik (München) 

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany COSMO 02, Chicago (18-21 September 2002)

The CP Problem of Strong Interactions 

Standard 

QCD Lagrangian 

contains 

a CP violating term 

Induces a neutron 

electric dipole moment 

(EDM) much in excess 

of experimental limits 

Characterizes degenerate 

QCD ground state (Θ ( vacuum) 

Θ 

L 

d 

CP 

n 

10 − 

< 10 − 

< 

α 

= 

− 

s 

2 

π 

( Θ 

− 

arg 

det 

M 

) q 

E 

color 

⋅ 

B 

color 

�� 

0 

≤ 

Θ 

≤ 

2 

π 

− 

16 

Θ 

− 

25 

≈ 

25 

≈ Θ 

10 

e 

cm 

≈ 

µ 

n < 10 

e 

cm 

10 

2 

10 

2 n < 

9 

Why so small ? 

Phase of Quark 

Mass Matrix 


Dynamical Solution 

Peccei & Quinn 1977 - Wilczek 1978 - Weinberg 1978 

Θ 

Re-interpret Re interpret as 

a dynamical variable 

(scalar field) 

α 

L ⋅ 

CP 

a 

Θ 

→ 

a 

( 

x 

) 

f 

a 

Pseudo-scalar 

Pseudo scalar axion field 

Peccei-Quinn Peccei Quinn scale, 

Axion decay constant 

a 

( 

x 

) 

= − 

s 

Θ 

E 

color 

B 

2 

color 

2π 

π 

color − 

s E 

color 

⋅ 

B 

2 

color 

2π 

π f 

color 

a 

gluon 

gluon 

Axions generically couple to 

gluons and thus mix with π0 �� Axion 

mass 

�� Pion 

mass 

�� f 

~ 

× π 

�� 

& couplings �� ~ 

�� 

& couplings�� 

× π f �� 

�� & couplings �� π 

�� 

�� & couplings�� 

π ≈ 

93 

MeV 

�� 

�� 

�� f 

Pion decay constant 

a 

V(a) 

Θ 

= 

0 

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany COSMO 02, Chicago (18-21 September 2002) 

α 

a 

Potential (mass term) 

induced by L CP drives 

a(x) to CP-conserving 

CP conserving 

minimum 

CP-symmetry 

CP symmetry 

dynamically restored

Windows of Opportunity 

Axions Alternatives 

Solve strong CP problem 

by Peccei-Quinn 

Peccei Quinn 

dynamical symmetry restoration 

Cosmic cold dark matter candidate 

Direct detection possible 

Search for new physics at E >> TeV 

in low-energy low energy experiments 

(Axions Nambu-Goldstone Nambu Goldstone boson of 

spontaneously broken symmetry) 

Massless up-quark up quark 

Spontaneous CP violation 

Fine tuning 

Supersymmetric particles 

Superheavy particles 

Sterile Neutrinos 

Many others … 

(but usually not experimentally 

accessible) 

Neutrino masses (see-saw) (see saw) 

Proton decay 

Monopoles 

Deviation from Newton’s Law 

(e.g. large extra dimensions) 


Axion Production in the Early Universe 

YES 

Thermal relics 

Ω 

1 

a ∝ ma 

∝ f 

−1 

a ∝ ma 

∝ f 

− 

a 

For ma a ~ 10 eV 

hot dark matter 

(Excluded by 

astrophysical limits) 

Thermalization at T < ΛQCD QCD ? 

NO for fa > O(10 > O(108 GeV) 

Non-thermal Non thermal relics from QCD epoch 

Ω 

1 

. 

175 

Ω 

175 1. 

175 

a ∝ fa 

∝ m 

−1. 

175 

a ∝ fa 

∝ m 

− 

a 

T ~ f a 

UPQ(1) PQ(1) 

spontaneously 

broken 

Higgs field settles 

in “Mexican hat” 

T ~ ΛQCD QCD

Axion Production in the Early Universe 

YES 

Thermal relics 

Ω 

1 

a ∝ ma 

∝ f 

−1 

a ∝ ma 

∝ f 

− 

a 

For ma a ~ 10 eV 

hot dark matter 

(Excluded by 

astrophysical limits) 

Thermalization at T < ΛQCD QCD ? 

NO for fa > O(10 > O(108 GeV) 

Non-thermal Non thermal relics from QCD epoch 

Ω 

1 

. 

175 

Ω 

175 1. 

175 

a ∝ fa 

∝ m 

−1. 

175 

a ∝ fa 

∝ m 

− 

a 

For ma a ~ 100 µeV eV T ~ cold f dark matter 

a 

Reheating T after UPQ(1) PQ inflation (1) spontaneously 

m a 

Experiments 

Astrophysical Axion Bounds 

Stellar Evolution Cosmology 

10 3 10 6 10 9 10 

10 12 [GeV 

keV eV 

meV µeV eV 

Tele 

scope 

Globular clusters 

(a-γ-coupling) 

(a coupling) 

Too many 

events 

HDM 

Too much 

energy loss 

SN 1987A (a-N-coupling) 

(a coupling) 

GeV] f a 

Axion dark matter possible 

(Low reheat T scenario) 

DM o.k. Too much DM 

(String scenario) 

Direct 

search 


Experimental Search for Galactic Axions 

DM axions 

Velocities in galaxy 

Energies therefore 

Axion Haloscope (Sikivie 1983) 

ma = 10−3000 10 3000 µeV eV 

va ≈ 10 -3 c 

Ea ≈ (1 ± 10 -6 ) ma m 

Bext ext ≈ 8 Tesla 

Microwave 

Resonator 

Q ≈ 10 5 

Primakoff Conversion 

a 

γ 

Bext ext 

Cavity 

overcomes 

momentum 

mismatch 

Power 

Frequency ma Microwave Energies 

(1 GHz ≈ 4 µeV eV) 

Axion Signal 

Power of galactic axion signal 

2 

× 

−21 

V �� B �� Q 

4× 

−21 

V �� B �� Q 

4 10 

W 

3 

�� 

0 

. 

22 

3 

22m 

m �� 8 

. 

5 

T 

�� 10 

�� m 

�� 

× �� 

�� 

�� a �� 

× 

�� 

�� 

�� 

�� a 

�� 2πGHz 

�� 

�� 

�� 2πGHz 

�� 

�� 

�� 5 

× 

10 

Thermal noise of 

cavity & detector 


5 

ρ 

a 

− 

25 

g 

/ 

cm 

3 

�� 

�� 

�� 

��

Axion Dark Matter Searches 

Limits/sensitivities assume axions are the galactic dark matter 

4 

3 

KSVZ 

E/N = 0 

2 

5 

1 

DFSZ 

E/N = 8/3 

1. Rochester-Brookhaven 

Rochester Brookhaven- 

Fermilab 

PRD 40 (1989) 3153 

2. University of Florida 

PRD 42 (1990) 1297 

3. US Axion Search 

(Livermore) 

ApJL 571 (2002) L27 

4. ADMX (Livermore) 

Phys Repts 325 (2000) 1 

5. CARRACK I (Kyoto) 

preliminary 

hep-ph/0101200 

hep ph/0101200 

6. CARRACK II (Kyoto) 

hep-ph/0101200 

hep ph/0101200 


6

Axion Dark Matter Searches 

Limits/sensitivities assume axions are the galactic dark matter 

4 

3 

2 

1 

1. Rochester-Brookhaven 

Rochester Brookhaven- 

Fermilab 

PRD 40 (1989) 3153 

Steve Asztalos: 

2. University of Florida 

PRD 42 (1990) 1297 

KSVZ 

The U.S. 5dark 

dark matter 6 axion 3. US search 

Axion Search 

E/N Thursday, = 0 

Thursday, 2:50 p.m. 

DFSZ 

E/N = 8/3 

(Livermore) 

ApJL 571 (2002) L27 

4. ADMX (Livermore) 

Phys Repts 325 (2000) 1 

5. CARRACK I (Kyoto) 

preliminary 

hep-ph/0101200 

hep ph/0101200 

6. CARRACK II (Kyoto) 

hep-ph/0101200 

hep ph/0101200 


m a 

Experiments 

Astrophysical Axion Bounds 

Stellar Evolution Cosmology 

10 3 10 6 10 9 10 

10 12 [GeV 

keV eV 

meV µeV eV 

Tele 

scope 

Globular clusters 

(a-γ-coupling) 

(a coupling) 

Too many 

events 

HDM 

Too much 

energy loss 

SN 1987A (a-N-coupling) 

(a coupling) 

GeV] f a 

Axion dark matter possible 

(Low reheat T scenario) 

DM o.k. Too much DM 

(String scenario) 

Direct 

search 


Gauge hierarchy problem solved by 

supersymmetry 

LSP good CDM candidate 

Axinos as Dark Matter 

Strong CP problem solved by 

Peccei-Quinn Peccei Quinn mechanism 

Axion good CDM candidate 

Axino also good and generic CDM candidate 

For Peccei-Quinn Peccei Quinn scale in allowed 

range and a low reheating T after 

inflation, thermal processes and decay 

of NLSP can produce CDM axinos 

No obvious experimental search 

possible 

Covi, Kim & Roszkowski 

PRL 82 (1999) 4180 

Covi, Kim, Kim & Roszkowski 

JHEP 0105 (2001) 

Covi, Roszkowski & Small 

hep-ph/0206119 

hep ph/0206119 


Gauge hierarchy problem solved by 

supersymmetry 

LSP good CDM candidate 

Axinos as Dark Matter 

Strong CP problem solved by 

Peccei-Quinn Peccei Quinn mechanism 

Axion good CDM candidate 

Axino also good and generic CDM candidate 

Laura Covi: 

Bounds on T R from axino CDM 

Friday, 4:40 p.m. 

For Peccei-Quinn Peccei Quinn scale in allowed 

range and a low reheating T after 

inflation, thermal processes and decay 

of NLSP can produce CDM axinos 

No obvious experimental search 

possible 

Covi, Kim & Roszkowski 

PRL 82 (1999) 4180 

Covi, Kim, Kim & Roszkowski 

JHEP 0105 (2001) 

Covi, Roszkowski & Small 

hep-ph/0206119 

hep ph/0206119 


Axion Axion-photon photon-coupling coupling g gaγγ γγ 

γγ [GeV 

Axion-Like Like Particles that Couple to Photons 

10 -4 

10 -6 

GeV -1 ] Axion 

10 -8 

10 -10 10 

10 -12 12 

10 -14 14 

10 -16 16 

10 -7 

General low-mass low mass (pseudo)scalars 

that couple to photons 

What are they good for? 

What are the limits? 

How can they be detected? 

10 -6 

DFSZ DFSZ model model 

KSVZ KSVZ model model 

10 -5 10 -4 

10 -3 

10 -2 

10 -1 

Axion mass m a [eV eV] 

Axion Line 

1 10 100 


π0 π0

Two-Photon Two Photon Coupling and its Consequences 

Particles with two-photon two photon vertex: 

Neutral pions (π0 ), Gravitons 

Axions (a) and similar hypothetical particles 

Two-photon 

Two photon 

decay 

Primakoff 

Effect 

Magnetically 

induced vacuum 

birefringence 

Γ 

a 

γ 

= 

g 

2 

a 

γ 

m 

64 

π 

3 

a 

γ 

Conversion of photons into 

pions, gravitons or axions, axions, 

or the reverse 

In addition to QED 

Cotton-Mouton 

Cotton Mouton-effect effect 

L a 

γ 

g 

a 

Photon 

Coalescence 

= γ 

E 

⋅ 

B 

a 



γγ [GeV GeV -1 ] 

10 -4 

10 -6 

10 -8 

10 -10 10 

10 -12 12 

10 -14 14 

10 -16 16 

10 -7 

Limits on Axion-Photon 

Axion Photon-Coupling Coupling 

10 -6 

Laser 

PVLAS PVLAS expected 

expected 

DM 

Search 

HB Stars in Globular Clusters 

Future Future 



10 -5 10 -4 

10 -3 

10 -2 

10 -1 


Axion Line 

1 10 100 


Dimming of Supernovae without Cosmic Acceleration 

Csáki, Kaloper & Terning 

PRL 88 (2002) 161302, PLB 535 (2002) 33 

Erlich & Grojean 

hep-ph/0111335 

hep ph/0111335 

Deffayet, Harari, Uzan 

& Zaldarriaga, hep-ph/0112118 

hep ph/0112118 

Mörtsell, Bergström & Goobar 

astro-ph/0202153 

astro ph/0202153 

Christensson & Fairbairn 



Axion-photon 

Axion photon-oscillations oscillations in intergalactic B-field field domains dim photon flux 

�� Effect grows linearly with distance 

�� Saturates at equipartition between photons and axions (unlike grey grey 

dust) 

Mixing matrix 

Domain size ~ 1 Mpc 

Field strength ~ 1 nG 

a-γ-coupling coupling ~ 10 -10 

Axion mass < 10 -16 16 eV 

�� 2 

g 

1 

2 

a B �� 

− 

1 �� ω g 

pl γ ω �� 1 

2 

a B �� 

− 

1 �� ω 

10. 

8ne 

0. 

15 ga 

B �� 

pl γ ω�� 

�� 

�� 

10. 

8ne 

ω 0. 

15 gaγB 

�� 

�� −1 

= 

�� ω 

γ 

−1 

Mpc 

2ω 

�� 

�� 

2 

�� 2 

−4 

2 −1 

gaγB 

m �� 

�� 

= 

�� Mpc 

2ω 

�� 

�� 

2 

−4 

2 −1 

a 

0. 

15 gaγB 

7. 

8 10 m �� 

�� 

× aω 

�� 

gaγBω 

m �� 

�� 

a 

0. 

15 g 

�� aγB 

7. 

8 10 m �� 

�� 

× aω 

�� 

ω 

�� 

�� 

10 GeV -1 

Photon energy ~ 1 eV 

Electron density 

~ 10 -7 cm -3 

(average baryon density) 

Chromaticity depends 

sensitively on assumed 

values and distribution 

of n e and B 


Dimming of Supernovae without Cosmic Acceleration 

Csáki, Kaloper & Terning 

PRL 88 (2002) 161302, PLB 535 (2002) 33 

Erlich & Grojean 

hep-ph/0111335 

hep ph/0111335 

Deffayet, Harari, Uzan 

& Zaldarriaga, hep-ph/0112118 

hep ph/0112118 

Mörtsell, Bergström & Goobar 



Christensson & Fairbairn 



Axion-photon 

Axion photon-oscillations oscillations in intergalactic B-field field domains dim photon flux 

�� Effect grows linearly with distance 

�� Saturates at equipartition between photons and axions (unlike grey grey 

dust) 

Mixing matrix 

Domain size ~ 1 Mpc 

Field strength ~ 1 nG 

a-γ-coupling coupling ~ 10 -10 

Axion mass < 10 -16 16 eV 

John Terning: 

Dimming Supernovae via Axions 

Thursday, 4:00 p.m. 

�� 2 

g 

1 

2 

a B �� 

− 

1 �� ω g 

pl γ ω �� 1 

2 

a B �� 

− 

1 �� ω 

10. 

8ne 

0. 

15 ga 

B �� 

pl γ ω�� 

�� 

�� 

10. 

8ne 

ω 0. 

15 gaγB 

�� 

�� −1 

= 

�� ω 

γ 

−1 

Mpc 

2ω 

�� 

�� 

2 

�� 2 

−4 

2 −1 

gaγB 

m �� 

�� 

= 

�� Mpc 

2ω 

�� 

�� 

2 

−4 

2 −1 

a 

0. 

15 gaγB 

7. 

8 10 m �� 

�� 

× aω 

�� 

gaγBω 

m �� 

�� 

a 

0. 

15 g 

�� aγB 

7. 

8 10 m �� 

�� 

× aω 

�� 

ω 

�� 

�� 

10 GeV -1 

Photon energy ~ 1 eV 

Electron density 

~ 10 -7 cm -3 

(average baryon density) 

Chromaticity depends 

sensitively on assumed 

values and distribution 

of n e and B 


γ 

Primakoff 

production 

Sun 

Search for Solar Axions 

a 

Axion flux 

Axion Helioscope (Sikivie 1983) 

a 

Axion-Photon 

Axion Photon-Oscillation 

Oscillation 

Magnet S 


N 

�� Tokyo Axion Helioscope 

(Results since 1998) 

�� CERN Axion Solar Telescope (CAST) 

(in preparation) 

Alternative Technique: 

Bragg conversion in crystal 

Experimental limits on solar axion flux 

from dark-matter dark matter experiments 

(SOLAX, COSME, DAMA, ...) 

γ

Tokyo Axion Helioscope 

~ 3 m 

S.Moriyama, M.Minowa M. Minowa, , T.Namba T. Namba, , Y.Inoue, Y.Takasu Y. Takasu & A.Yamamoto, 

PLB 434 (1998) 147 


New Limits from Tokyo Axion Helioscope 

Y. Inoue et al., 



Axion-photon 

Axion photon 

transition region 

filled with 

pressurized gas 

to give photons 

an effective mass 

(avoid momentum 

mismatch) 




10 -4 

10 -6 

10 -8 

10 -10 10 

10 -12 12 

10 -14 14 

10 -16 16 

10 -7 




expected 

Helio 

seis 

Tokyo Helioscope 

mology 

10 -6 

Laser 

DM 

Search 

Future Future 



10 -5 10 -4 

10 -3 

10 -2 

10 -1 


Sun 

Bragg 

HB 

Stars 

1 10 100 


Telescope 

Axion Line

Formerly 

Solar olar 

Axion xion 

Telescopic elescopic 

ANtenna ANtenna 

CERN ERN Axion xion Solar olar Telescope elescope (CAST) 

Solar axion search at CERN using a decommissioned LHC test magnet 

magne 

E.Arik, D.Autiero, F.Avignone, K.Barth, S.Bowyer, H.Bräuninger, H.Br uninger, R.Brodzinski, 

J.Carmona, F.Cataneo, S.Cebrian, G.Celebi, S.Cetin, J.Collar, R.Creswick, 

R. Creswick, 

M.Delattre, A.Delbart, R.de Oliveira, L.di Lella, N.Erduran, G.Fanourakis, 

G.Fanourakis, 

H.Farach, C.Fiorini, E.Garcia, T.Geralis, I.Giomataris, T.Girard, T.Girard, 

S.Gninenko, 

N.Goloubev, M.Hasinoff, D.Hoffmann, I.Irastorza, J.Jacoby, K.Jakovcic, 

K.Jakovcic, 

M.Knopf, M.Krcmar, Z.Krecak, A.Ljubicic, A.Longoni, G.Lutz, G.Luzon, G.Luzon, 

A.Mailov, 

V.Matveev, H.Miley, A.Morales, J.Morales, M.Mutterer, S.Nussinov, S.Nussinov, 

A.Ortiz de 

Solorzano, W.Pitts, A.Placci, J.Puimedon, G.Raffelt, H.Riege, M.Sampietro, 

M. Sampietro, 

M.Sarsa, M.Stipcevic, C.Thomas, R.Thompson, P.Valko, J.Villar, B.Vullierme, 

B.Vullierme, 

L.Walckiers, W.Wilcox, K.Zachariadou, K.Zioutas 


Horizontally Moving Platform 


Recent Picture of CAST (12 August 2002) 


X-Ray Ray Focussing to Increase Signal-To Signal To-Noise Noise 

With imaging x-ray x ray mirror, solar image ~ 1 mm 2 

compared with 14 cm 2 magnet bore 

Abrixas x-ray x ray satellite, failed 

shortly after launch in 1999 

Vast background 

suppression 

One spare x-ray x ray mirror available 

from Zeiss, has been tested at 

Panther facility of MPE Garching 




10 -4 

10 -6 

10 -8 

10 -10 10 

10 -12 12 

10 -14 14 

10 -16 16 

10 -7 




expected 

Helio 

seis 


mology 

CAST Sensitivity 

10 -6 

Laser 

DM 

Search 

Future Future 



10 -5 10 -4 

10 -3 

10 -2 

10 -1 


+Gas 

Sun 

Bragg 

HB 

Stars 

1 10 100 


Telescope 

Axion Line




10 -4 

10 -6 

10 -8 

10 -10 10 

10 -12 12 

10 -14 14 

10 -16 16 

10 -7 




expected 

Helio 

seis 


mology 

CAST Sensitivity 

10 -6 

Laser 

DM 

Search 

Future Future 



10 -5 10 -4 

10 -3 

10 -2 

10 -1 


+Gas 

Sun 

Bragg 

HB 

Stars 

1 10 100 


Telescope 

Axion Line

Georg G. Raffelt Max-Planck-Institut für Physik (München) - Fermilab

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