Why we need Lab Experiments to search for Alps Joerg Jaeckel 1 E. Masso, J. Redondo 2 F. Takahashi,...
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Transcript of Why we need Lab Experiments to search for Alps Joerg Jaeckel 1 E. Masso, J. Redondo 2 F. Takahashi,...
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 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 Relatives: ALPsThe Relatives: ALPs
• Pseudoscalars: not very creative... ...Simply throw away m-g-relation
• Scalars: as above but with coupling to instead of
Tests are based on Tests are based on couplingcoupling
• Primakoff process (in the sun)
Ion or electron
Photon(plasma)
ALP (leaving the sun)
CAST
Primakoff in the LabPrimakoff in the Lab
• Primakoff process (in the lab)
Photon(LASER)
ALP (leaving undetected)
External B-field
ProblemProblem
• ALP interpretation of PVLAS in severe conflict with astrophysical bounds
Can we reconcile these results?
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
Light shining through Light shining through wallswalls
• VUV-FEL + Accelerator Magnets• XFEL + Hera Magnets
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!
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 :
RegenerationRegeneration
• Primakoff goes the other way around
ALP(from sun)
Photon (to detector)
External B-field