MeV-GeV $\gamma$-ray telescopes probing gravitino LSP with coexisting axino NLSP as dark matter in the $\mu\nu$SSM

TL;DR

This paper investigates the potential for future MeV-GeV gamma-ray telescopes to detect signals from gravitino LSP and axino NLSP dark matter particles within the $ u$SSM framework, highlighting possible double-line signatures.

Contribution

It introduces a novel analysis of combined gravitino and axino dark matter detection prospects in the $ u$SSM, emphasizing the detectability of double-line gamma-ray signals.

Findings

Parameter space regions detectable by future gamma-ray telescopes.

Potential for double-line gamma-ray signals from axino NLSP and gravitino LSP.

Feasibility of probing supersymmetric dark matter in the $ u$SSM with gamma-ray observations.

Abstract

In $R$-parity violating supersymmetry, the gravitino as the lightest supersymmetric particle (LSP) is a good candidate for dark matter, with the interesting characteristic to be detectable through $\gamma$-ray telescopes. We extend this analysis considering an axino next-to-LSP (NLSP) as a coexisting dark matter particle contributing with a detectable signal in the $\gamma$-ray spectrum. The analysis is carried out in the framework of the $\mu\nu$SSM, which solves the $\mu$ problem reproducing simultaneously neutrino data only with the addition of right-handed neutrinos. We find that important regions of the parameter space can be tested by future MeV-GeV $\gamma$-ray telescopes through the line signal coming from the decay of the axino NLSP into photon-neutrino. In a special region, a double-line signal from axino NLSP and gravitino LSP is possible with both contributions detectable.