Constraining self-interacting dark matter with the full dataset of PandaX-II

TL;DR

This paper reports on searches for self-interacting dark matter with a light mediator using PandaX-II data, setting strong constraints on dark matter-nucleon interactions and combining these with cosmological observations to refine dark matter models.

Contribution

First comprehensive search for SIDM with a light mediator using PandaX-II data, providing new upper limits and combining direct detection with cosmological constraints.

Findings

No significant excess found over background.

Set strong upper limits on dark matter-nucleon coupling.

Combined constraints from direct detection and cosmology.

Abstract

Self-interacting Dark Matter (SIDM) is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies. Many SIDM models predict the existence of a light force carrier that mediate strong dark matter self-interactions. If the mediator couples to the standard model particles, it could produce characteristic signals in dark matter direct detection experiments. We report searches for SIDM models with a light mediator using the full dataset of the PandaX-II experiment, based on a total exposure of 132 tonne-days. No significant excess over background is found, and our likelihood analysis leads to a strong upper limit on the dark matter-nucleon coupling strength. We further combine the PandaX-II constraints and those from observations of the light element abundances in the early universe, and show that direct detection and cosmological probes can provide complementary constraints on dark matter models with a light mediator.