Dirac right-handed sneutrino dark matter and its signature in the gamma-ray lines

TL;DR

This paper proposes a model where Dirac right-handed sneutrinos serve as dark matter candidates, capable of producing gamma-ray lines detectable by Fermi-LAT through one-loop annihilation processes.

Contribution

It introduces a neutrinophilic Higgs model with leptonic couplings that naturally yields the correct dark matter relic density and predicts gamma-ray line signatures from sneutrino annihilation.

Findings

Dark matter relic density can be achieved via thermal freeze-out.

One-loop annihilation into gamma-ray lines can be significant.

Model explains potential gamma-ray signals observed by Fermi-LAT.

Abstract

We show that a Dirac right-handed scalar neutrino can be weakly interacting massive particle in the neutrinophilic Higgs model. When the additional Higgs fields couple only to the leptonic sector through neutrino Yukawa couplings, the right number of relic density of dark matter can be obtained from thermal freeze-out of the dark matter annihilation into charged leptons and neutrinos. At present, this annihilation is suppressed by the velocity of dark matter. However one-loop annihilation cross section into $\gamma\gamma$ can be larger than that of the helicity suppressed annihilation into fermions, because relevant coupling constants are different. Hence, gamma-ray line signal which might have been observed in the Fermi-LAT is also able to be explained by its annihilation.