HEP Theory Journal Cliff

Axions, stimulated decay, and CMB spectral distortions

Gonzalo Alvarez Alonso

McGill

The decay of axions into two photons is subject to Bose enhancement effects due to the bosonic nature of the particles involved. This can dramatically shrink the lifetime of the axions in the presence of a photon background, as is present in the early universe. Although the combination of the expansion of the universe and in-medium effects makes axions sufficiently long-lived to be dark matter, the decay of even a small fraction of the axion dark matter abundance may leave an observable imprint in the CMB energy spectrum.