The leptophilic dark matter in the Sun: the minimum testable mass

TL;DR

This paper explores leptophilic dark matter interactions with electrons in the Sun, using Monte Carlo methods to determine the minimum mass detectable via neutrino signals, revealing differences from nucleon interactions.

Contribution

It introduces a detailed Monte Carlo analysis of leptophilic dark matter in the Sun and establishes the minimum testable mass for DM-electron interactions based on neutrino observations.

Findings

Minimum detectable DM-electron mass is about 1 GeV lower than for nucleon interactions.

A larger cross section (~100 times) is needed to saturate the annihilation signal.

Monte Carlo methods provide a more accurate distribution than semi-analytic approximations.

Abstract

The physics of the solar dark matter (DM) that are captured and thermalise through the DM-nucleon interaction has been extensively studied. In this work, we consider the leptophilic DM scenario where the DM particles interact exclusively with the electrons through the axial-vector coupling. We investigate relevant phenomenologies in the Sun, including its capture, evaporation and thermalisation, and we calculate the equilibrium distribution using the Monte Carlo methods, rather than adopting a semi-analytic approximation. Based on the analysis, we then determine the minimum testable mass for which the DM-electron coupling strength can be probed via the neutrino observation. Compared to the case of the DM-nucleon interaction, it turns out that minimum detectable mass of the DM-electron interaction is roughly 1 GeV smaller, and a cross section about two orders of magnitude larger is required for the saturation of the annihilation signal.