A new parameter space study of the singlet fermionic cold dark matter model

TL;DR

This study explores a singlet fermionic dark matter model with a scalar mediator, analyzing its parameter space, relic abundance, and experimental constraints, concluding it is excluded by current direct detection experiments.

Contribution

The paper provides a detailed parameter space analysis of a singlet fermionic dark matter model with a scalar mediator, including relic abundance and experimental constraints.

Findings

Dark matter candidate excluded by XENON100, LUX, COUPP, PICASSO data.

Relic abundance constraints restrict parameter space.

Perturbation theory valid only at specific parameter regions.

Abstract

We consider the standard model (SM) extended by a gauge singlet fermion as cold dark matter (SFCDM) and a gauge singlet scalar (singlet Higgs) as a mediator. The parameter space of the SM is enlarged by seven new ones. We obtain the total annihilation cross section of singlet fermions to the SM particles and singlet Higgs at tree level. Regarding the relic abundance constraint obtained by WMAP observations, we study the dependency on each parameter separately, for dark matter masses up to 1 TeV. In particular, the coupling of SFCDM to singlet Higgs $g_s$, the SFCDM mass $m_\psi$, the second Higgs mass $m_{h_2}$, and the Higgs bosons mixing angel $\theta$ are investigated accurately. Three other parameters play no significant role. For a maximal mixing of Higgs bosons or at resonances, $g_s$ is applicable for the perturbation theory at tree level. We also obtain the scattering cross section of SFCDM off nucleons and compare our results with experiments which have already reported data in this mass range; XENON100, LUX, COUPP and PICASSO collaborations. Our results show that the SFCDM is excluded by these experiments for choosing parameters which are consistent with perturbation theory and relic abundance constraints.