Why we need Lab Experiments to search for Alps Joerg Jaeckel 1 E. Masso, J. Redondo 2 F. Takahashi, A. Ringwald 1 1 DESY 2 Universitat Autonoma de Barcelona

Axions and their Relatives

Axions 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 to

The 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.

Astrophysical Bounds

Tests are based on coupling Primakoff proces

Tests are based on coupling Primakoff process (in the sun) Ion or electron Photon (plasma) ALP (leaving the sun) CAST

Bounds coherence

PVLAS

Primakoff in the Lab Primakoff process (in the lab) Photon (LASER) ALP (leaving undetected) External B-field

Dichroism Coupling Determine coupling

Result

Problem ALP interpretation of PVLAS in severe conflict with astrophysical bounds Can we reconcile these results?

Evading Astrophysical bounds

Suppress Production Idea: In the center of the sun the environment is different from a lab environment. –High temperature –Large virtuality q 2 –High density (compared to vacuum) –Large F  in Primakoff prozess –High neutrino flux

Phenomenological Approach Simplest phenomenological approach: Make ALP-parameters environment dependent m a >T forbids production kinematically g small suppresses production via the coupling

Radial suppression suppressed unsuppressed Since ,T,,j depend only on the radius this suppresses production up to a certain radius X

Wiggling Room

We need Lab Experiments

Light shining through walls VUV-FEL + Accelerator Magnets XFEL + Hera Magnets

Can Test PVLAS final

Conclusions

Conclusions 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

How much suppression needed? The coupling compatible with PVLAS is g -1 PVLAS » 10 5 GeV Lifetime argument: g -1 life » GeV CAST: g -1 CAST » GeV

Is the Sun Extreme? At 0% Radius:T » K ¼ 1200eV  » 150 g/cm 3 h |q| i& 290eV At 79% Radius:T » K ¼ 117eV  » g/cm 3 h |q| i& 9eV At 97% Radius:T » K ¼ 12.5eV  » g/cm 3 h |q| i& 1.4eV The absolute values for T,  in the sun are far from extreme!

Compared to PVLAS Density up to g/cm 3 Temperature T. 300K » 0.025eV |q| » eV Compared to the environment of PVLAS: The sun is hot and dense! And the average |q| is high. Room for exotic possibilities!!! X

Is the Sun Extreme? At 79% Radius: T » K ¼ 117eV  » g/cm 3 At 91% Radius: T » K ¼ 42eV  » g/cm 3 The absolute values for T,  in the sun are far from extreme!

A (Reasonable) Realization One (more realistic) possibility for suppression would be a form factor: In PVLAS |q| » eV In the sun h |q| i» keV

A (Reasonable) Realization One (more realistic) possibility for suppression would be a form factor: Motivations: –Composite particle –Extra Dimensions –String Theory??

A 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 Coherence External field has to absorb momentum q Production rate Momentum transfer back

Which suppression 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(  ) or m(  )? M(  ) m(  ) Light shining through walls exp can distinguish!

Different signals back

QCD 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 Axion Make  dynamical degree of freedom Axion a.  a evolves automatically toward h a i =0! a is coupled to :

Bound from Star Lifetimes

Regeneration Primakoff goes the other way around ALP (from sun) Photon (to detector) External B-field

CAST back

An electric dipole moment is generated by messy instanton effects?