Field Evolution leading to hybrid inflation

Abstract

In general the onset of hybrid inflation requires an extremely homogeneous field configuration at the end of Planck era. The field ϕorthogonal to the inflaton σmust be zero with high accuracy over the range exceeding the initial horizon size \sim m_{Pl}^{-1} by about two orders of magnitude. We consider a supersymmetric model that permits the decay of the oscillating field ϕinto light particles. We study the field evolution and find that the requirement of the extreme homogeneity can be relaxed. However, the field ϕmust still be smaller than the inflaton by a factor of order 1 over a region far exceeding the initial horizon size.