Low-mass right-handed sneutrino dark matter: SuperCDMS and LUX
  constraints and the Galactic Centre gamma-ray excess
  Recent results from direct and indirect searches for dark matter (DM) have
motivated the study of particle physics models that can provide weakly
interacting massive particles (WIMPs) in the mass range 1-50 GeV. Viable
candidates for light WIMP DM must fulfil stringent constraints. On the one
hand, the observation at the LHC of a Higgs boson with Standard Model
properties set an upper bound on the coupling of light DM particles to the
Higgs, thereby making it difficult to reproduce the correct relic abundance. On
the other hand, the recent results from direct searches in the CDMSlite,
SuperCDMS and LUX experiments have set upper constraints on the DM scattering
cross section. In this paper, we investigate the viability of light
right-handed sneutrino DM in the Next-to-Minimal Supersymmetric Model (NMSSM)
in the light of these constraints. To this aim, we have carried out a scan in
the NMSSM parameter space, imposing experimental bounds on the Higgs sector and
low-energy observables, such as the muon anomalous magnetic moment and
branching ratios of rare decays. We demonstrate that the enlarged Higgs sector
of the NMSSM, together with the flexibility provided by the RH sneutrino
parameters, make it possible to obtain viable RH sneutrino DM with a mass as
light as 2 GeV. We have also considered the upper bounds on the annihilation
cross section from Fermi LAT data on dwarf spheroidal galaxies, and extracted
specific examples with mass in the range 8-50 GeV that could account for the
apparent low-energy excess in the gamma-ray emission at the Galactic Centre.
Then, we have computed the theoretical predictions for the elastic scattering
cross-section of RH sneutrinos. Finally, after imposing the recent bounds from
SuperCDMS and LUX, we have found a wide area of the parameter space that could
be probed by future low-threshold direct detection experiments.
