  We consider the production of right-handed (RH) sneutrino dark matter in a
model of Dirac neutrino where neutrino Yukawa coupling constants are very
small. Dark matter RH sneutrinos are produced by scatterings and decays of
thermal particles in the early Universe without reaching thermal equilibrium
due to the small Yukawa couplings. We show that not only decays of thermal
particles but also the thermal scatterings can be a dominant source as well as
non-thermal production in a scenario with light sneutrinos and charged sleptons
while other supersymmetric particles are heavy. We also discuss the
cosmological implications of this scenario.
