Annihilation of singlet fermionic dark matter into two photons

TL;DR

This paper analyzes a singlet fermionic dark matter model extended with a singlet Higgs, calculating the annihilation cross section into two photons and comparing it with Fermi-Lat observations.

Contribution

It provides an analytical calculation of the dark matter annihilation into two photons within this extended model and compares the results with observational data.

Findings

Calculated the pair annihilation cross section into two photons.

Derived the coupling versus dark matter mass consistent with relic abundance.

Compared theoretical predictions with Fermi-Lat observational limits.

Abstract

We consider an extension of the standard model in which a singlet fermionic particle, to serve as cold dark matter, and a singlet Higgs are added. We perform a reanalysis on the free parameters. In particular, demanding a correct relic abundance of dark matter, we derive and plot the coupling of the singlet fermion with the singlet Higgs, $g_s$, versus the dark matter mass. We analytically compute the pair annihilation cross section of singlet fermionic dark matter into two photons. The thermally averaged of this cross section is calculated for wide range of energies and plotted versus dark matter mass using $g_s$ consistent with the relic abundance condition. We also compare our results with the Fermi-Lat observations.