EFT Approach of Inelastic Dark Matter for Xenon Electron Recoil Detection

TL;DR

This paper develops an effective field theory framework to interpret the XENON1T electron recoil excess as inelastic dark matter interactions, constraining model parameters and exploring UV completions.

Contribution

It introduces an EFT approach to inelastic dark matter detection via electron recoil, fitting experimental data and deriving new constraints on DM properties and interactions.

Findings

Constrained DM mass-splitting to 2.1-3.3 keV with best fit at 2.8 keV.

Derived bounds on DM mass and interaction scale consistent with XENON1T excess.

Explored possible UV completions for the effective DM-lepton interactions.

Abstract

Measuring dark matter (DM) signals via electron recoil provides an important means for direct detection of light DM particles. The recent XENON1T anomaly with electron recoil energy around $\,E_R^{}\!=\!(2-3)$keV can be naturally explained by DM inelastic scattering which injects energy to the recoiled electrons and gives a narrow peak structure in the recoil spectrum. We present an effective field theory (EFT) approach to exothermic inelastic DM signals for the Xenon electron recoil detection. For relatively heavy mediator, we fairly formulate the DM-lepton interactions by effective contact operators with two DM fields $(X,\,X')$ and two leptons. Using the XENON1T data, we fit the electron recoil spectrum and constrain the allowed scalar DM mass-splitting as $\,2.1\,\text{keV}\!<\!\Delta m\!<\!3.3\,\text{keV}$ (95%C.L.), with the best fit $\,\Delta m \!=\! 2.8$keV. We analyze the relic abundance produced by such effective DM-electron contact interaction. To provide both the DM relic abundance and the XENON1T excess, we derive new constraints on the DM mass and the UV cutoff scale of DM effective interactions. Finally, we study possible UV completions for the effective DM-lepton contact interactions.