Towards string theory expectations for photon couplings to axionlike particles
Towards string theory expectations for photon couplings to axionlike particles
ALP-photon couplings are modeled in large ensembles of string vacua and random matrix theories. In all cases, the effective coupling increases polynomially in the number of ALPs, of which hundreds or thousands are expected in the string ensembles, many of which are ultralight. The expected value of the couplings $g_{a\gamma\gamma}\simeq …