On thermal production of self-interacting dark matter

We consider thermal production mechanisms of self-interacting dark matter in models with gauged z 3 symmetry. a complex scalar dark matter is stabilized by the z 3, that is the remnant of a local dark u(1) d . light dark matter with large self-interaction can be produced from thermal freeze-out in the presence of sm-annihilation, simp and/or forbidden channels. we show that dark photon and/or dark higgs should be relatively light for unitarity and then assist the thermal freeze-out. we identify the constraints on the parameter space of dark matter self-interaction and mass in cases that one or some of the channels are important in determining the relic density.