Abstract
Dark Matter may reside in sector without Standard Model (SM) gauge interactions. One way in which such a dark sector can still impact SM particles through non-gravitational interactions is via the “photon portal” in which a dark photon kinetically mixes with the ordinary SM photon. We study the implications of this setup for electron recoil events at TEXONO reactor and nuclear recoil events at the COHERENT experiment. We find that the recent COHERENT data rules out previously allowed regions of parameter space favored by the thermal relic hypothesis for the DM abundance. When mapped onto the DM-electron cross section, we find that COHERENT provides the leading direct constraints for DM masses < 30 MeV.
Highlights
JHEP11(2018)066 where Fμν, Hh, and N are respectively hidden sector field strengths, Higgses, and fermions
In this paper we study the impact of the photon portal for light DM, in which the Standard Model (SM) photon kinetically mixes with a U(1) dark photon [1]
In this paper we studied the implications of recent data from both TEXONO and COHERENT for the photon portal interaction of light DM
Summary
We assume that the hidden sector U(1) gauge group spontaneously breaks to give the dark photon Vμ a mass. In our analysis of TEXONO and COHERENT data we will always assume the mass hierarchy, mV > 2mX , such that the decay V → X X is allowed. This assumption has ramifications for the thermal relic abundance of DM. The annihilation to EM charged states as predicted in this setup, leads to strong constraints from CMB data [12]. While the CMB constraints are completely negligible for p-wave annihilation they can still be relevant at limiting the particle-to-antiparticle ratio for asymmetric DM [13,14,15]. For simplicity here we focus on fermionic DM, and expect the derived TEXONO and COHERENT bounds to be similar for scalar DM
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