Direct detection of Higgs portal for light self-interacting dark matter

TL;DR

This paper explores the potential for direct detection of light, sub-GeV self-interacting dark matter via Higgs portal interactions, analyzing constraints and detection methods like cosmic-ray accelerated scattering and electron recoil.

Contribution

It introduces new direct detection limits for sub-GeV SIDM with a scalar mediator considering cosmic-ray and electron recoil methods, highlighting the detectability conditions and constraints.

Findings

Detectability requires a sizable mediator-Higgs mixing angle.

CRDM approach is not feasible within the Higgs-portal model.

Electron recoil detection could provide independent constraints.

Abstract

Self-interacting dark matter (SIDM) can address the small-scale anomalies and previous researches focused on such a SIDM heavier than GeV, for which the self-scattering cross-section is in the quantum resonance region and has a non-trivial velocity dependence. For a SIDM lighter than GeV, the self-scattering cross-section falls within the Born region. In this work, considering the constraints from CMB, BBN and the DM relic density, we investigate the direct detection of the Higgs portal for a sub-GeV SIDM with a scalar mediator. For this end, we consider two approaches : one is the cosmic-ray accelerated dark matter (CRDM) scattering off the nucleon, the other is the electron recoil caused by the halo dark matter. We present direct detection limits for the parameter space of light SIDM and scalar mediator. We find that the detectability in either approach needs a sizable mediator-Higgs mixing angle ($\sin\theta$) which is larger than one for the CRDM approach and larger than $10^{-3}$ for the electron recoil approach. While the former case cannot be realized in the Higgs-portal light SIDM model with a scalar mediator, the latter case may also be constrained by some astrophysical observations or beam dump experiment. Anyway, even if other constraints are quite stringent, the direct detection may provide independent limits for such a sub-GeV SIDM.