Gauge Singlet Scalars as Cold Dark Matter
John McDonald
TL;DR
This paper analyzes a minimal Standard Model extension that adds gauge-singlet scalars interacting through a Higgs-portal coupling $\lambda_S S^{\dagger}S H^{\dagger}H$ as a cold dark matter candidate. It computes the thermal relic density $\Omega_{S} h^{2}$ across $(m_S, \lambda_S)$ using the Lee–Weinberg framework and enumerates annihilation channels to $hh$, $WW$, $ZZ$, and fermions, highlighting how the relic density scales with the number of singlets. It then assesses direct detection via elastic scattering on Ge nuclei and indirect detection via neutrinos from the Sun and Earth, finding current bounds weakly constrain the thermal relic region, while next-generation detectors can probe substantial portions for $m_S \lesssim 50$ GeV and larger masses with adequate detector size. The results indicate that a future $10^4\ \mathrm{m}^2$ neutrino detector or a 1 km$^2$ observatory could significantly test or exclude the thermal relic SDM up to the TeV scale for favorable Higgs masses, making this Higgs-portal scenario a testable dark matter framework.
Abstract
In light of recent interest in minimal extensions of the Standard Model and gauge singlet scalar cold dark matter, we provide an arXiv preprint of the paper, published as Phys.Rev. D50 (1994) 3637, which presented the first detailed analysis of gauge singlet scalar cold dark matter.