Why we need Lab Experiments to search

for Alps

Joerg JaeckelJoerg Jaeckel11

E. Masso, J. Redondo2

F. Takahashi, A. Ringwald1

1 DESY 2 Universitat Autonoma de

Barcelona

Axions and their Relatives

Axions in a SlideAxions in a Slide

• Axions appear in the „standard solution“ to the strong CP problem

• May be dark matter• May dim supernovae• ...• Axions are coupled to :

The Coupling toThe Coupling to

The Relatives: ALPsThe Relatives: ALPs

• Pseudoscalars: not very creative... ...Simply throw away m-g-relation

• Scalars: as above but with coupling to instead of

Commercials

Your CP is violated too strongly?

Use Axion!

New! With special cleaning particles and extra strong photon coupling.

AstrophysicalBounds

Tests are based on Tests are based on couplingcoupling

• Primakoff proces

Tests are based on Tests are based on couplingcoupling

• Primakoff process (in the sun)

Ion or electron

Photon(plasma)

ALP (leaving the sun)

CAST

BoundsBounds

coherence

PVLAS

Primakoff in the LabPrimakoff in the Lab

• Primakoff process (in the lab)

Photon(LASER)

ALP (leaving undetected)

External B-field

DichroismDichroism

• Coupling

Determine coupling

ResultResult

ProblemProblem

• ALP interpretation of PVLAS in severe conflict with astrophysical bounds

Can we reconcile these results?

Evading Astrophysical bounds

Suppress ProductionSuppress Production

• Idea: In the center of the sun the environment is different from a lab environment.– High temperature– Large virtuality q2

– High density (compared to vacuum)

– Large F in Primakoff prozess– High neutrino flux

Phenomenological Phenomenological ApproachApproach

• Simplest phenomenological approach:Make ALP-parameters environment dependent

ma>T forbids production

kinematically

g smallsuppresses production

via the coupling

Radial suppressionRadial suppression

suppressed

unsuppressed

• Since ,T,<F>,j depend only on the radius this suppresses production up to a certain radius

X

Wiggling RoomWiggling Room

We need

Lab Experiments

Light shining through Light shining through wallswalls

• VUV-FEL + Accelerator Magnets• XFEL + Hera Magnets

Can Test PVLASCan Test PVLAS

final

Conclusions

ConclusionsConclusions

• Axions well motivated but still undetected

• ALP‘s not so well motivated but may have been detected by PVLAS

• Strong astrophysical bounds may be circumvented

• We need Lab experiments!

Near future lab experiments are able to

test interesting regions for ALPs

Is the Sun Extreme?Is the Sun Extreme?

• At 79% Radius:T»1.4

106K¼117eV» 9.8 10-2g/cm3

• At 91% Radius:T»5 105K¼42eV» 2 10-2g/cm3

The absolute values for T, in the sun are far from extreme!

A (Reasonable) A (Reasonable) RealizationRealization

• One (more realistic) possibility for suppression would be a form factor:

• In PVLAS |q|» 10-6 eV• In the sun h|q|i» keV

A (Reasonable) A (Reasonable) RealizationRealization

• One (more realistic) possibility for suppression would be a form factor:

• Motivations:– Composite particle– Extra Dimensions– String Theory??

A Low Energy ScaleA Low Energy Scale

• Requirement for enough suppression sets the scale for the form factor in the range »meV-eV

Compared to „fundamental“ physics very low scale!

back

A Note on CoherenceA Note on Coherence

• External field has to absorb momentum q

• Production rate• Momentum transfer

15 10 5 0 5 10 150

0.025

0.05

0.075

0.1

0.125

0.15

back

Which suppression Which suppression mechanism?mechanism?

• E.g. can we distinguish between m() and M()?

• M() suppression does not affect the equation of motion after the particle is produced!

• m() acts like a (large) potential for the particle.

M(M() or m() or m()?)?

0 0.5 1 1.5 2x

0.2

0.4

0.6

0.8

1

1.2

1.4x

M()

m()

Light shining through walls exp can distinguish!

Different signalsDifferent signals

back

QCD CP ViolationQCD CP Violation

• In QCD CP is violated by the term

generated, e.g. by instantons

• 0 would lead to an electric dipole moment for the neutron

Unnatural!!

Solution: The AxionSolution: The Axion

• Make dynamical degree of freedom Axion a.

a evolves automatically toward hai=0!

• a is coupled to :

Bound from Star LifetimesBound from Star Lifetimes

RegenerationRegeneration

• Primakoff goes the other way around

ALP(from sun)

Photon (to detector)

External B-field

CASTCAST

back

An electric dipole moment is generated by messy

instanton effects?