The Fate of SUSY Flat Directions and their Role in Reheating
Abstract
We consider the role of supersymmetric flat directions in reheating the Universe after inflation. Flat directions can develop large vevs during inflation, which can potentially affect reheating by slowing down scattering processes among inflaton decay products or by coming to dominate the energy density of the Universe. Both effects occur only if flat directions are sufficiently long-lived. The computation of their perturbative decay rate, and a simple estimate of their nonperturbative decay have led to the conclusion that this is indeed the case. In contrast, we show that flat directions decay quickly through nonperturbative channels in realistic models. The mass matrix for MSSM excitations around a flat direction has nondiagonal entries, which vary with the phase of the (complex) flat direction. The quasi-periodic motion of the flat direction results in a strong parametric resonance, leading to the rapid depletion of the flat direction within its first few rotations. This precludes any significant role for the flat directions in reheating the Universe after inflation in models in which the inflaton decays perturbatively.Keywords
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