Boosted Dark Matter Interpretation of the XENON1T Excess

TL;DR

This paper suggests that boosted dark matter particles could explain the XENON1T excess of keV electron recoil events, with a simple model involving a heavy vector mediator and potential directional detection features.

Contribution

It introduces boosted dark matter as a novel explanation for the XENON1T excess, including a simple model and the prediction of daily modulation signals.

Findings

Boosted dark matter can produce keV electron recoils consistent with XENON1T data.

A simple model with a heavy vector mediator supports the required scattering cross sections.

Daily modulation of the signal offers a way to distinguish it from backgrounds.

Abstract

We propose boosted dark matter (BDM) as a possible explanation for the excess of keV electron recoil events observed by XENON1T. BDM particles have velocities much larger than those typical of virialized dark matter, and, as such, BDM-electron scattering can naturally produce keV electron recoils. We show that the required BDM-electron scattering cross sections can be easily realized in a simple model with a heavy vector mediator. Though these cross sections are too large for BDM to escape from the Sun, the BDM flux can originate from the Galactic Center or from halo dark matter annihilations. Furthermore, a daily modulation of the BDM signal will be present, which could not only be used to differentiate it from various backgrounds, but would also provide important directional information for the BDM flux.