Gamma Rays from Top-Mediated Dark Matter Annihilations

TL;DR

This paper explores gamma ray lines from top-mediated dark matter annihilations, demonstrating their potential as signals of thermal relic dark matter and analyzing their observability considering constraints from experiments and collider data.

Contribution

It introduces realistic UV-completions of the Higgs in Space model, highlighting the rich gamma ray line structure and emphasizing the importance of one-loop continuum contributions.

Findings

Gamma ray lines can be consistent with thermal relic dark matter.

One-loop continuum gamma rays can dominate over line signals.

Model constraints from dark matter searches and LHC are compatible with observable signals.

Abstract

Lines in the energy spectrum of gamma rays are a fascinating experimental signal, which are often considered "smoking gun" evidence of dark matter annihilation. The current generation of gamma ray observatories are currently closing in on parameter space of great interest in the context of dark matter which is a thermal relic. We consider theories in which the dark matter's primary connection to the Standard Model is via the top quark, realizing strong gamma ray lines consistent with a thermal relic through the forbidden channel mechanism proposed in the Higgs in Space Model. We consider realistic UV-completions of the Higgs in Space and related theories, and show that a rich structure of observable gamma ray lines is consistent with a thermal relic as well as constraints from dark matter searches and the LHC. Particular attention is paid to the one loop contributions to the continuum gamma rays, which can easily swamp the line signals in some cases, and have been largely overlooked in previous literature.