Features in the primordial power spectrum of double D-term inflation

Recently, there has been some interest for building supersymmetric models o f double inflation. These models, realistic from a particle physics point o f view, predict a broken-scale-invariant power spectrum of primordial cosmo logical perturbations, that may explain eventual nontrivial features in the present matter power spectrum. In previous works, the primordial spectrum was calculated using analytic slow-roll approximations. However, these mode ls involve a fast second-order phase transition during inflation, with a st age of spinodal instability, and an interruption of slow-roll. For our prev ious model of double D-term inflation, we simulate numerically the evolutio n of quantum fluctuations, taking into account the spinodal modes, and we s how that the semiclassical approximation can be employed even during the tr ansition, due to the presence of a second inflaton field. The primordial po wer spectrum possesses a rich structure, and possibly, a non-Gaussian spike on observable scales. (C) 2000 Elsevier Science B.V. All rights reserved.