Novel Search for absorption of ultra-light fermionic dark matter on electron with cosmic ray boost

TL;DR

This paper proposes a novel method to detect ultra-light fermionic dark matter by leveraging cosmic ray-boosted dark matter particles, enabling constraints on very low mass ranges using existing XENONnT data.

Contribution

It introduces a new search strategy using cosmic ray-boosted dark matter to extend sensitivity to lower mass ranges, filling a gap in current detection methods.

Findings

Placed constraints on dark matter-electron cross section for masses between 10^-5 and 1 keV.

Achieved the lowest mass constraints among DM direct detection experiments using ionizing signals.

Utilized the XENONnT dataset to explore previously untested low-mass dark matter parameter space.

Abstract

The search for the absorption of fermionic dark matter (DM) on electron is hindered by a partial or complete loss of sensitivity for the mass of DM ($m_\chi$) below $\mathcal{O} (10)$ keV. We introduce a novel search using a small but high-energy portion of DM boosted by cosmic rays, and the loss of sensitivity is circumvented because the subsequent absorption within the detector imparts to the target electron not only $m_\chi$ but also substantial $T_\chi$. The one-sided 90\% confidence level constraints on ($\sigma_e v_\chi$) are derived with the XENONnT public dataset for $m_\chi$ $\in$ (1$\times$10$^{-5}$--1) keV which has not been explored yet. Our results have placed constraints on DM at the lowest $m_\chi$ currently achievable among the DMDD experiments utilizing ionizing signals from DM interactions within the detectors.