Singlino-dominated dark matter in $Z_3$-NMSSM

TL;DR

This paper explores singlino-dominated dark matter in the $Z_3$-NMSSM, analyzing its properties, interactions, and parameter space, and discusses implications for direct detection experiments and future searches.

Contribution

It provides analytical formulas for dark matter abundance and cross sections, and surveys the parameter space using Bayesian methods to identify viable scenarios in the $Z_3$-NMSSM.

Findings

Dark matter can achieve correct abundance via annihilation or co-annihilation.

Small $ ext{lambda}$ and cancellations can suppress detection signals.

Future experiments like PandaX-4T can test these scenarios.

Abstract

Singlino-dominated dark matter properties are investigated in the $Z_3$ Next-to-Minimal Supersymmetric Standard Model, producing superweak interactions with nucleons involved in dark matter direct detection experiments. Approximate analytical formulas describing the dark matter abundance and cross section in the scattering with nucleons are used to illustrate a dependence on theoretical parameters in neutralino and Higgs sectors. It is shown that the measured abundance requires a sizable singlet--doublet Higgs coupling parameter $\lambda$, while the experimental detection results prefer a small $\lambda$. The parameter space is then surveyed using a nest sampling technique guided by a likelihood function containing various observables in dark matter, Higgs, and B physics, such as the abundance and the scattering cross section. It is demonstrated that dark matter can achieve the correct abundance through $\tilde{\chi}_1^0 \tilde{\chi}_1^0 \to t \bar{t}$ or co-annihilation with higgsinos. The former process provides significantly larger Bayesian evidence than the latter, but this will be examined by the near-future PandaX-4T experiment. If the experiment shows no signs of dark matter, it will become highly disfavored. Furthermore, four cases are summarized to suppress dark matter scattering with nucleons, namely, a small $\lambda$ and three kinds of cancellation between different contributions.