Implications of the XENON1T Excess on the Dark Matter Interpretation

TL;DR

This paper explores boosted dark matter scenarios with various mediators to explain the XENON1T electron recoil excess, identifying parameter regions consistent with existing bounds and highlighting the mediator's role in the interpretation.

Contribution

It systematically analyzes different mediator types and dark matter boosts, providing a general method applicable to dark matter direct detection data interpretation.

Findings

Boosted dark matter can explain the XENON1T excess depending on mediator type.

Parameter regions consistent with bounds are identified for various mediator scenarios.

The mediator type significantly influences the preferred mass and coupling scales.

Abstract

The dark matter interpretation for a recent observation of excessive electron recoil events at the XENON1T detector seems challenging because its velocity is not large enough to give rise to recoiling electrons of $\mathcal{O}({\rm keV})$. Fast-moving or boosted dark matter scenarios are receiving attention as a remedy for this issue, rendering the dark matter interpretation a possibility to explain the anomaly. We investigate various scenarios where such dark matter of spin 0 and 1/2 interacts with electrons via an exchange of vector, pseudo-scalar, or scalar mediators. We find parameter values not only to reproduce the excess but to be consistent with existing bounds. Our study suggests that the scales of mass and coupling parameters preferred by the excess can be mostly affected by the type of mediator, and that significantly boosted dark matter can explain the excess depending on the mediator type and its mass choice. The method proposed in this work is general, and hence readily applicable to the interpretation of observed data in the dark matter direct detection experiment.