A Search for Light Fermionic Dark Matter Absorption on Electrons in PandaX-4T

TL;DR

This paper reports a search for sub-MeV fermionic dark matter absorption on electrons using PandaX-4T data, setting new direct detection limits on interaction couplings in specific mass ranges.

Contribution

First direct detection limits for fermionic dark matter absorption on electrons with axial-vector and vector interactions in the keV mass range.

Findings

No significant dark matter signals observed.

Established the strongest direct detection limits in certain keV mass ranges.

Sensitivity surpasses some astrophysical bounds for specific interactions.

Abstract

We report a search on a sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the 0.63 tonne-year exposure collected by PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background. The data are interpreted into limits to the effective couplings between such dark matter and electrons. For axial-vector or vector interactions, our sensitivity is competitive in comparison to existing astrophysical bounds on the decay of such dark matter into photon final states. In particular, we present the first direct detection limits for an axial-vector (vector) interaction which are the strongest in the mass range from 25 to 45 (35 to 50) keV/c$^2$.