Electronic Direct Detection of Light Dark Matter with Intermediate-Mass Mediators

TL;DR

This paper explores the sensitivity of electron-based dark matter detection experiments to intermediate-mass mediators, extending the understanding beyond traditional light and heavy mediator limits, and provides publicly available computational tools.

Contribution

It introduces a detailed analysis of mediator mass ranges affecting detection sensitivity and updates the EXCEED-DM tool for broader application.

Findings

Sensitivity to dark matter varies over three orders of magnitude in mediator mass.

Calculated background-free sensitivity for Si and Ge targets, including DAMIC-M projections.

Provided publicly accessible code for further research and validation.

Abstract

Recent years have seen dramatic improvements in the sensitivity of electron-based direct detection experiments. Typically, the sensitivity to dark matter scattering is determined in the light and heavy mediator mass limits. In this paper we show that the light and heavy mediator mass limits are not separated by a single scale, but instead can be separated by up to three orders of magnitude in mediator mass for sub-GeV mass dark matter. We calculate the background-free sensitivity in Si and Ge targets, and a projected DAMIC-M sensitivity, to sub-GeV mass dark matter models with ``intermediate-mass" mediators between the light and heavy mediator limits. This allows us to determine the precise range of mediator masses that electron-based direct detection experiments are sensitive to when the dark matter relic abundance is generated via freeze-in. We make the calculations presented here publicly available in an updated release of EXCEED-DM (https://github.com/tanner-trickle/EXCEED-DM).