MSSM flat direction inflation: slow roll, stability, fine-tuning and reheating

Abstract

We consider low scale slow roll inflation driven by the gauge-invariant flatdirections udd and LLe of the minimally supersymmetric standard model at thevicinity of a saddle point of the scalar potential. We study the stability of thesaddle point and the slow roll regime by considering radiative and supergravitycorrections. The latter are found to be harmless, but the former require a modestfine-tuning of the saddle point condition. We show that, while the inflaton decaysalmost instantly, full thermalization occurs late, typically at a temperatureT≈107 GeV, so that there is no gravitino problem. We also compute the renormalization grouprunning of the inflaton mass and relate it to slepton masses that may be within thereach of the LHC and could be precisely determined in a future linear colliderexperiment.