Right-handed sneutrino dark matter in the NMSSM
  We study the properties of the right-handed sneutrino and its viability as a
WIMP dark matter candidate in an extended version of the NMSSM in which a
right-handed neutrino superfield is included with a coupling to the singlet
Higgs in order to provide non-vanishing Majorana neutrino masses. We perform a
systematic study of the parameter space, including LEP constraints and
experimental bounds on low-energy observables. We investigate the conditions
under which the right-handed sneutrino has the correct relic abundance and the
dominant annihilation channels. Next we calculate the theoretical predictions
for the sneutrino-proton elastic scattering cross section and compare it with
present and future experimental sensitivities. We find that sneutrinos with a
mass in the range of 5-200 GeV can reproduce the observed dark matter relic
density without being excluded by direct dark matter searches and for natural
values of the input parameters. Interestingly, the predicted scattering cross
section is generally within the reach of future experiments. Finally, we
comment on the possible implications for collider physics.
