Gamma-ray signal from Dark Matter Annihilation mediated by mixing scalar mediators

TL;DR

This paper explores how mixing scalar mediators influence gamma-ray signals and detection prospects of a specific Majorana dark matter model, highlighting the effects of mixing angles and CP-violation on observable signals.

Contribution

It introduces a detailed analysis of the impact of scalar mediator mixing and CP-violation phases on gamma-ray signals and detection strategies for Majorana dark matter.

Findings

Mixing angle alters internal bremsstrahlung features.

Mixing angle affects gamma-ray line flux ratios.

CP-violation causes polarization asymmetry in gamma-ray signals.

Abstract

We present here a study of the direct and indirect detection prospects of a generic dark matter simplified model, in which the Majorana dark matter interacts only with a Standard Model lepton and a pair of uncolored mixing scalar mediators. We first show that the mixing angle significantly changes the feature of internal bremsstrahlung, as well as the flux ratio of $\gamma\gamma$ and $\gamma Z$ line signals. The $CP$-violation phase will introduce an polarization asymmetry in the $\gamma\gamma$ final state. Then we study the direct detection prospect and discuss the complimentarity of these two search strategies.