Fits to the Fermi-LAT GeV excess with RH sneutrino dark matter: implications for direct and indirect dark matter searches and the LHC

TL;DR

This paper demonstrates that right-handed sneutrino dark matter within the NMSSM can explain the Fermi-LAT Galactic Centre gamma-ray excess while satisfying current experimental constraints, and discusses implications for future searches.

Contribution

It provides a comprehensive analysis of the parameter space where RH sneutrino dark matter explains the GCE, including full annihilation spectra and experimental constraints, which was not done in prior model-independent studies.

Findings

Best fit at 64 GeV RH sneutrino mass annihilating into light pseudoscalars

Good fits achieved with annihilation into four-body final states

Many scenarios are testable with upcoming gamma-ray and collider experiments

Abstract

We show that the right-handed (RH) sneutrino in the NMSSM can account for the observed excess in the Fermi-LAT spectrum of gamma rays from the Galactic Centre, while fulfilling all the current experimental constraints from the LHC as well as from direct and indirect dark matter searches. We have explored the parameter space of this scenario, computed the gamma ray spectrum for each phenomenologically viable solution and then performed a chi^2 fit to the excess. Unlike previous studies based on model independent interpretations, we have taken into account the full annihilation spectrum, without assuming pure annihilation channels. Furthermore, we have incorporated limits from direct detection experiments, LHC bounds and also the constraints from Fermi-LAT on dwarf spheroidal galaxies (dSphs) and gamma ray spectral lines. In addition, we have estimated the effect of the most recent Fermi-LAT reprocessed data (Pass 8). In general, we obtain good fits to the GCE when the RH sneutrino annihilates mainly into pairs of light singlet-like scalar or pseudoscalar Higgs bosons that subsequently decay in flight, producing four-body final states and spectral features that improve the goodness of the fit at large energies. The best fit (chi^2=20.8) corresponds to a RH sneutrino with a mass of 64 GeV which annihilates preferentially into a pair of light singlet-like pseudoscalar Higgs bosons (with masses of order 60 GeV). Besides, we have analysed other channels that also provide good fits to the excess. Finally, we discuss the implications for direct and indirect detection searches paying special attention to the possible appearance of gamma ray spectral features in near future Fermi-LAT analyses, as well as deviations from the SM-like Higgs properties at the LHC. Remarkably, many of the scenarios that fit the GCE can also be probed by these other complementary techniques.