Modulino Dark Matter and the INTEGRAL 511 keV Line

TL;DR

This paper proposes a supersymmetric model extension with singlets that naturally explains the INTEGRAL 511 keV gamma-ray line through dark matter decay, predicting associated gamma-ray signals from the galactic halo.

Contribution

It introduces a minimal supersymmetric extension with singlets that accounts for the INTEGRAL signal via modulino decay, embedding in a GUT framework.

Findings

Decay of heavier modulino produces electron-positron pairs matching the INTEGRAL line.

Model predicts diffuse gamma rays from internal bremsstrahlung in the galactic halo.

Mass splittings of singlets are naturally at the MeV scale due to chiral symmetry breaking.

Abstract

In this paper we present a simple extension of the minimal supersymmetric standard model [MSSM] which "naturally" produces the INTEGRAL photon signal. The model can be embedded in an SU(5) grand unified theory [GUT] with gauge mediated SUSY breaking. The new ingredients are the addition of several MSSM singlets/moduli. While the masses of the singlets are at the weak scale, their mass splittings are suppressed by chiral symmetry breaking and naturally lie around an MeV. The decay of the heavier modulino to the lighter one with the associated production of electron - positron pairs explains the INTEGRAL signal. Finally, the detection of diffuse gamma rays from internal bremsstrahlung in the galactic halo would be a suggestive indication of dark matter decays associated with the 511 keV line, and is an unambiguous additional prediction of this model.