Probing the axion-photon coupling: phenomenological and experimental perspectives. A snowmass white paper

Understand

We present a brief overview of the ongoing searches for the axion particle via its coupling to photons.

• Both the classical QCD axions and more recently proposed Axion-Like-Particles are considered.
• Astrophysical bounds on the axion-photon coupling come from considerations of stellar energy loss during Helium burning, in both low- and high-mass stars.
• Helioscopes look for back-conversion of solar axions into x-ray photons in strong laboratory magnetic fields.