The linear response theory approach to the sub-GeV dark matter in the Sun

TL;DR

This paper applies linear response theory to model sub-GeV dark matter scattering in the Sun, highlighting the importance of in-medium effects for accurate detection predictions in semiconductor experiments.

Contribution

It extends the linear response formulation to solar medium interactions, incorporating in-medium effects into dark matter scattering calculations.

Findings

In-medium effects significantly influence DM scattering in the Sun.

Derived formulae enable precise prediction of solar-accelerated DM spectra.

The approach applies to both heavy and light mediator scenarios.

Abstract

In recent years, the importance of the electronic in-medium effect in the sub-GeV dark matter (DM) direct detection has been recognized and a coherent formulation of the DM-electron scattering based the linear response theory has been well established in the literature. In this paper, we apply the formulation to the scattering between DM particles and solar medium, and it is found that the dynamic structure factor inherently incorporate the particle-particle scattering and in-medium effect. Using this tool and taking a benchmark model as an example, we demonstrate how the in-medium effect affect the scattering of DM particles in the Sun, in both the heavy and light mediator limit. Formulae derived in this work lay the foundation for accurately calculating the spectra of solar-accelerated DM particles, which is of particular importance for the detection of DM particles via plasmon in semiconductor targets.