Phenomenology of Dark Matter in Chiral U(1)$_X$ Dark Sector

P. Ko, Takaaki Nomura

Published 2016-07-21Version 1

We consider dark matter physics in a model for dark sector with extra dark U(1)$_X$ gauge symmetry. The dark sector is composed of exotic fermions that are charged under both dark U(1)$_X$ and the standard model SU(3)$_C \times$U(1)$_Y$ gauge groups,as well as SM singlet complex scalars $\Phi$ and $X$ with nonzero U(1)$_X$ charge. In this model, there are two dark matter candidates, a scalar and a fermion dark matter both of which are stabilized by accidental $Z_2$ symmetry. Their thermal relic density, direct and indirect detection constraints are discussed in detail and we search for the parameter space of the model accommodating dark matter observations. We also show that the 750 GeV diphoton excess can be explained by the scalar field associated with dark U(1)$_X$ breaking in a way consistent with dark matter physics. In addition, implications to collider physics are discussed focusing on production cross section of the scalar boson.