Conditions for a successful right-handed Majorana sneutrino curvaton

We consider the conditions which must be satisfied for a Majorana RH sneutrino, a massive right-handed (RH) sneutrino associated with the seesaw mechanism of Majorana neutrino masses, to play the role of the curvaton. Planck-scale suppressed nonrenormalizable terms in the RH neutrino superpotential must be eliminated to a high-order if the RH sneutrino curvaton is to dominate the energy density before it decays, which can be achieved via an R-symmetry which is broken to R-parity by the Giudice-Maseiro mechanism. In order to evade thermalization of the curvaton condensate, one RH neutrino mass eigenstate must have small Yukawa couplings, corresponding to a lightest neutrino mass mν1 < or approx. 10-3 eV. A time-dependent lepton asymmetry will be induced in the RH sneutrino condensate by the Affleck-Dine mechanism driven by SUSY breaking B-terms associated with the RH neutrino masses. Requiring that the resulting baryon asymmetry and isocurvature perturbations are acceptably small imposes an upper bound on the RH neutrino mass. We show that a scenario consistent with all constraints is obtained for a RH neutrino mass in the range 102-104 GeV when the RH sneutrino decay temperature is greater than 100 GeV and lightest neutrino mass mν1≅10-3 eV. Larger RH neutrino masses are possible for smaller mν1. The resulting scenario is generally consistent with a solution of the cosmic string problem of D-term inflation