  Thermal leptogenesis in the canonical seesaw model in supersymmetry suffers
from the incompatibility of a generic lower bound on the mass scale of the
lightest right-handed neutrino and the upper bound on the reheating temperature
of the Universe after inflation. This is resolved by adding an extra singlet
superfield, with a discrete $Z_2$ symmetry, to the NMSSM (Next to Minimal
Supersymmetric Standard Model). This generic mechanism is applicable to any
supersymmetric model for lowering the scale of leptogenesis.

High Energy Physics - Phenomenology