GUT scale inflation and leptogenesis

Abstract

We reconsider supersymmetric hybrid inflation in which inflation is associated with the breaking of a gauge symmetry G to H, with the symmetry breaking scale M~10¹⁶ GeV. The models discussed feature a spectral index $n_s\geqslant0.98$ while $\textrm {d}n_{s}/\textrm {d}\ln k\lesssim10^{-3}$ and the tensor to scalar ratio $r\lesssim10^{-4}$. If G corresponds to SO(10) or one of its rank five subgroups, the observed baryon asymmetry is naturally explained via leptogenesis.