A Two-Singlet Model for Light Cold Dark Matter

TL;DR

This paper proposes a model extending the Standard Model with two scalar singlets, one as a stable dark matter particle and the other enabling new annihilation channels, making light dark matter viable and testable by upcoming experiments.

Contribution

It introduces a two-singlet scalar extension with a novel mechanism for lowering dark matter mass and analyzes its compatibility with relic abundance and experimental bounds.

Findings

Light dark matter is viable in most parameter regions.

Most allowed mass range will be tested by XENON1T.

The model predicts new annihilation channels affecting relic density.

Abstract

We extend the Standard Model by adding two gauge-singlet $\mathbb{Z}_{2}$% -symmetric scalar fields that interact with visible matter only through the Higgs particle. One is a stable dark matter WIMP, and the other one undergoes a spontaneous breaking of the symmetry that opens new channels for the dark matter annihilation, hence lowering the mass of the WIMP. We study the effects of the observed dark matter relic abundance on the annihilation cross section and find that in most regions of the parameters space, light dark matter is viable. We also compare the elastic scattering cross-section of our dark matter candidate off nucleus with existing (CDMSII and XENON100) and projected (SuperCDMS and XENON1T) experimental exclusion bounds. We find that most of the allowed mass range for light dark matter will be probed by the projected sensitivity of XENON1T experiment.