Gamma Ray Lines from a Universal Extra Dimension

TL;DR

This paper analyzes gamma-ray spectral lines from Kaluza--Klein Dark Matter in a 5D Universal Extra Dimensions model, extending previous work to include additional final states, which could help distinguish this model from others.

Contribution

It extends previous calculations of gamma-ray lines from 5D UED dark matter to include b3 Z and b3 H final states, providing a more complete spectral signature.

Findings

b3 b3 line signal is dominant among spectral lines.

b3 Z and b3 H lines are subdominant but important for model discrimination.

Spectral lines can help distinguish 5D UED from other dark matter models.

Abstract

Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into \gamma \gamma, but we extend these results to include \gamma Z and \gamma H final states. We find that these spectral lines are subdominant compared to the predicted \gamma \gamma signal, but they would be important as follow-up signals in the event of the observation of the \gamma \gamma line, in order to distinguish the 5d UED model from other theoretical scenarios.