Dirac dark matter with a charged mediator: a comprehensive one-loop analysis of the direct detection phenomenology

TL;DR

This paper provides a detailed one-loop analysis of how Dirac dark matter particles interact with nucleons via scalar mediators, revealing that current and future xenon detectors can probe most of the viable parameter space.

Contribution

It offers a comprehensive one-loop calculation of direct detection signals for Dirac dark matter with a charged mediator, including electromagnetic, electroweak, and Higgs exchange effects.

Findings

Current LUX limits strongly constrain the model.

Future xenon detectors will probe nearly all viable parameter space.

The model can potentially explain the Galactic GeV excess.

Abstract

We analyze the direct detection signals of a toy model consisting of a Dirac dark matter particle which couples to one Standard Model fermion via a scalar mediator. For all scenarios, the dark matter particle scatters off nucleons via one loop-induced electromagnetic and electroweak moments, as well as via the one-loop exchange of a Higgs boson. Besides, and depending on the details of the model, the scattering can also be mediated at tree level via the exchange of the scalar mediator or at one loop via gluon-gluon interactions. We show that, for thermally produced dark matter particles, the current limits from the LUX experiment on these scenarios are remarkably strong, even for dark matter coupling only to leptons. We also discuss future prospects for XENON1T and DARWIN and we argue that multi-ton xenon detectors will be able to probe practically the whole parameter space of the model consistent with thermal production and perturbativity. We also discuss briefly the implications of our results for the dark matter interpretation of the Galactic GeV excess.