Electrophilic dark matter with dark photon: from DAMPE to direct detection

TL;DR

This paper proposes a dark matter model explaining the DAMPE electron-positron excess via an electrophilic fermion stabilized by a dark U(1) symmetry, predicting a testable one-loop induced DM-nucleon cross section influenced by kinetic mixing.

Contribution

It introduces a novel electrophilic dark matter model linked to DAMPE data, highlighting the potential for detectable direct detection signals through one-loop processes and kinetic mixing effects.

Findings

The model can explain the DAMPE excess with appropriate Yukawa couplings.

A one-loop level DM-nucleon cross section can be generated, making direct detection feasible.

Kinetic mixing can significantly alter the DM-nucleon interaction strength.

Abstract

The electron-positron excess reported by the DAMPE collaboration recently may be explained by an electrophilic dark matter (DM). A standard model singlet fermion may play the role of such a DM when it is stablized by some symmetries, such as a dark $U(1)_X^{}$ gauge symmetry, and dominantly annihilates into the electron-positron pairs through the exchange of a scalar mediator. The model, with appropriate Yukawa couplings, can well interpret the DAMPE excess. Naively one expects that in this type of models the DM-nucleon cross section should be small since there is no tree-level DM-quark interactions. We however find that at one-loop level, a testable DM-nucleon cross section can be induced for providing ways to test the electrophilic model. We also find that a $U(1)$ kinetic mixing can generate a sizable DM-nucleon cross section although the $U(1)_X^{}$ dark photon only has a negligible contribution to the DM annihilation. Depending on the signs of the mixing parameter, the dark photon can enhance/reduce the one-loop induced DM-nucleon cross section.