Electromagnetic Catalysis of the Radiative Decay of the Axion

Abstract

The radiative decay of the axion $a\to \gamma \gamma$ is investigated in an external electromagnetic field in DFSZ model in which axion couples to both quarks and leptons at tree level. The decay probability is strongly catalyzed by the external field, namely, the field removes the main suppression caused by the smallness of the axion mass.

Comments: Minor revision, references added, to be published in Phys.Lett.B