Light dark matter in NMSSM and implication on Higgs phenomenology

TL;DR

This paper explores the possibility of very light neutralino dark matter within the NMSSM framework, analyzing experimental constraints and implications for Higgs boson decays, revealing viable parameter space and potential signatures.

Contribution

It demonstrates that light neutralino dark matter is compatible with current experiments and predicts associated light Higgs bosons affecting Higgs decay channels.

Findings

Neutralino dark matter can be as light as a few GeV.

Current XENON100 and CoGeNT data exclude significant parameter space.

Light Higgs bosons are necessary to satisfy relic density constraints.

Abstract

For the experimental search of neutralino dark matter, it is important to know its allowed mass and scattering cross section with the nucleon. In order to figure out how light a neutralino dark matter can be predicted in low energy supersymmetry, we scan over the parameter space of the NMSSM (next-to-minimal supersymmetric model), assuming all the relevant soft mass parameters to be below TeV scale. We find that in the parameter space allowed by current experiments the neutralino dark matter can be as light as a few GeV and its scattering rate off the nucleon can reach the sensitivity of XENON100 and CoGeNT. As a result, a sizable parameter space is excluded by the current XENON100 and CoGeNT data (the plausible CoGeNT dark matter signal can also be explained). The future 6000 kg-days exposure of XENON100 will further explore (but cannot completely cover) the remained parameter space. Moreover, we find that in such a light dark matter scenario a light CP-even or CP-odd Higgs boson must be present to satisfy the measured dark matter relic density. Consequently, the SM-like Higgs boson $h_{SM}$ may decay predominantly into a pair of light Higgs bosons or a pair of neutralinos so that the conventional decays like $h_{SM} -> \gamma \gamma$ is much suppressed.