Solar Reflection of Inelastic Dark Matter

TL;DR

This paper explores how solar-reflected inelastic dark matter can produce detectable signals in direct-detection experiments, providing new constraints on MeV-scale dark matter models through detailed simulations.

Contribution

It introduces a detailed Monte Carlo simulation framework for solar-reflected inelastic dark matter and evaluates its detectability in current experiments.

Findings

Experiments can set new constraints on MeV-scale inelastic dark matter.

Solar reflection significantly enhances the energy of dark matter particles for detection.

Simulations cover a range of dark matter masses and mass splittings.

Abstract

Solar-reflected dark matter (SRDM) consists of dark-matter particles up-scattered and accelerated by energetic electrons in the solar interior, producing a high-velocity tail that can enhance signals in direct-detection experiments, especially for MeV-scale masses. We consider an inelastic dark matter (iDM) model, in which solar scattering populates the excited state; subsequent de-excitation in terrestrial detectors releases the mass-splitting energy, substantially helping the energy release of the collision to be larger than the detector threshold. Using detailed Monte Carlo simulations, we generate the velocity and energy distributions of solar-reflected iDM over a range of dark-matter masses $m_\chi$ and mass splittings $\Delta$. We then compute event rates and energy depositions for current xenon and semiconductor experiments. Our results show that these experiments can place new constraints on the parameter space of MeV-scale iDM.