U-hybrid inflation in realistic particle physics models

Abstract

In ¹-hybrid inflation, a nonzero inflaton vacuum expectation value, induced by supersymmetry breaking is proportional to the gravitino mass m3/2, which can be exploited to resolve the minimal supersymmetric standard model (MSSM) ¹ problem. First, we show how this scenario can be successfully implemented in a simple U(1)B¡L extension of the standard model, with m3/2 » 1 ¡ 100 TeV and reheat temperature as low as 106 GeV, by employing a minimal renormalisable superpotential coupled with a well defined nonminimal Kähler potential. The tensor-to-scalar ratio r, a canonical measure of primordial gravity waves, in most cases, is less than or on the order of 10¡6 ¡10¡3. Then we investigate supersymmetric hybrid inflation in a realistic model based on the gauge symmetry SU(4)c £SU(2)L £SU(2)R. The MSSM ¹ term arises following Dvali, Lazarides, and Shafi, from the coupling of the MSSM electroweak doublets to a gauge singlet superfield, and plays an essential role in inflation. The primordial monopoles are inflated away by arranging that the SU(4)c £SU(2)L £SU(2)R symmetry is broken along the inflationary trajectory. The interplay between the (above) ¹ coupling, the gravitino mass, the reheating following inflation, and leptogenesis is discussed in detail. We explore regions of the parameter space that yield gravitino dark matter and observable gravity waves with the tensor-to-scalar ratio r » 10¡4 ¡10¡3. In the end, I present a realistic supersymmetric SO(10) model for the implementation of ¹-hybrid inflation.