GeV Scale Inelastic Dark Matter with Dark Photon Mediator via Direct Detection and Cosmological/Laboratory Constraints

TL;DR

This paper introduces a new GeV-scale inelastic dark matter model with a dark photon mediator, explaining recent experimental anomalies and outlining testable predictions within a constrained parameter space.

Contribution

It presents a novel anomaly-free inelastic dark matter model with a dark photon, compatible with current experiments and capable of explaining recent anomalies.

Findings

Resolved the XENON1T anomaly via electron recoil detection.

Predicted inelastic DM mass to be less than 1.5 GeV.

Identified viable parameter space considering relic abundance and laboratory constraints.

Abstract

We propose a new candidate of GeV scale inelastic dark matter (DM). Our construction has an anomaly-free $U(1)_X^{}$ gauge group with dark photon mediator, and can realize either scalar or fermionic inelastic DM. It is highly predictive and testable. We study the scattering rate of light inelastic DM with electrons in the XENON1T experiment and with nuclei in the XENON1T, CRESST-III, CDEX-1B and DarkSide-50 experiments. We resolve the recent XENON1T anomaly via electron recoil detection. Combining the XENON1T constraints from both electron recoils and nuclear recoils (including Migdal effect), we predict the inelastic DM mass $\lesssim 1.5$GeV. We further analyze the bounds by the DM relic abundance, the lifetime of the heavier DM component, and laboratory constraints, from which we identify the viable parameter space for the future probe. This provides an important benchmark for the theories and experimental tests of GeV scale inelastic DM.