Relaxed constraints for dark matter with axial coupling to a dark photon

Abstract

We present a new model of the dark sector involving Dirac fermion dark matter, with axial coupling to a dark photon which provides a portal to Standard Model particles. In the non-relativistic limit, this implies that the dominant effective operator relevant to direct detection is ${\cal O}_8$. The resulting event rate for direct detection is suppressed by either the dark matter velocity or the momentum transfer. In this scenario there are much wider regions of the dark parameter space that are consistent with all of the existing constraints associated with thermal relic density, direct detection and collider searches.