Light and Heavy Dark Matter Particles

TL;DR

This paper argues that reconciling a potential 511 keV line from the Galactic center with high-energy gamma-ray signals can be achieved by a two-component dark matter model inspired by N=2 supersymmetry. It introduces two stable neutral particles protected by independent R- and M-parities, assigning the light state as Light Dark Matter (LDM) to explain the 511 keV emission and the heavier state as Heavy Dark Matter (HDM) responsible for high-energy gamma rays. A light gauge boson U mediates LDM interactions, enabling velocity-suppressed annihilation in the present epoch while maintaining the correct relic density. The framework yields testable implications for astrophysical observations and collider experiments, and provides a coherent mechanism to satisfy both cosmological and gamma-ray constraints within a two-component DM paradigm.

Abstract

It has recently been pointed out that the 511 keV emission line detected by Integral/SPI from the bulge of our galaxy could be explained by annihilations of light Dark Matter particles into e^+ e^-. If such a signature is confirmed, then one might expect a conflict with the interpretation of very high energy gamma rays if they also turn out to be due to Dark Matter annihilations. Here, we propose a way to accomodate the existence of both signals being produced by Dark Matter annihilations through the existence of two stable (neutral) Dark Matter particles, as is possible in theories inspired from N=2 supersymmetry.