New Gamma-Ray Contributions to Supersymmetric Dark Matter Annihilation

TL;DR

This paper calculates electromagnetic radiative corrections to dark matter annihilation in supersymmetric models, revealing significant enhancements in gamma-ray signals that are crucial for upcoming gamma-ray telescope searches.

Contribution

It provides a comprehensive analysis of radiative corrections in MSSM and mSUGRA models, highlighting their impact on gamma-ray signatures and dark matter detection prospects.

Findings

Radiative corrections can boost gamma-ray yields by up to four orders of magnitude.

Near degeneracy between neutralino and tau sleptons enhances gamma-ray signals.

Internal bremsstrahlung can dominate over line signals in certain parameter regions.

Abstract

We compute the electromagnetic radiative corrections to all leading annihilation processes which may occur in the Galactic dark matter halo, for dark matter in the framework of supersymmetric extensions of the Standard Model (MSSM and mSUGRA), and present the results of scans over the parameter space that is consistent with present observational bounds on the dark matter density of the Universe. Although these processes have previously been considered in some special cases by various authors, our new general analysis shows novel interesting results with large corrections that may be of importance, e.g., for searches at the soon to be launched GLAST gamma-ray space telescope. In particular, it is pointed out that regions of parameter space where there is a near degeneracy between the dark matter neutralino and the tau sleptons, radiative corrections may boost the gamma-ray yield by up to three or four orders of magnitude, even for neutralino masses considerably below the TeV scale, and will enhance the very characteristic signature of dark matter annihilations, namely a sharp step at the mass of the dark matter particle. Since this is a particularly interesting region for more constrained mSUGRA models of supersymmetry, we use an extensive scan over this parameter space to verify the significance of our findings. We also re-visit the direct annihilation of neutralinos into photons and point out that, for a considerable part of the parameter space, internal bremsstrahlung is more important for indirect dark matter searches than line signals.