LIGHT SPINLESS PARTICLE COUPLED TO PHOTONS

A pseudoscalar or scalar particle phi that couples to two photons but not to leptons, quarks, and nucleons would have effects in most of the experiments searching for axions, since these are based on the alpha gamma gamma coupling. We examine the laboratory, astrophysical, and co smological constraints on phi and study whether it may constitute a su bstantial part of the dark matter. We also generalize the phi interact ions to possess SU(2) x U(1) gauge invariance, and analyze the phenome nological implications.