Astrophysical bounds on very-low-mass axions

Abstract

We consider the contribution to stellar energy loss that would result from the existence of a recently proposed very-low-mass (≲1 eV) axion. We calculate the energy loss rate of hydrogen-burning stars and of red giants from very-light-axion production through the Primakoff process. The result is an upper bound of about ${10}^{-2\mathrm{}}$ eV on the mass of such a particle. We also consider briefly the cosmic background produced by the decay products of primordial axions, and the possibility of laboratory measurements of the long-range force a low-mass pseudoscalar boson would create.