PUB - Publikationen an der Universität Bielefeld

We analyse models of inflation in which isocurvature perturbations presentduring inflation are converted into the primordial curvature perturbationduring instant preheating. This can be due to an asymmetry between the fieldspresent either during inflation or during preheating. We consider all theconstraints that the model must satisfy in order to be theoretically valid andto satisfy observations. We show that the constraints are very tight in all ofthe models proposed and special initial conditions are required for the modelsto work. In the case where the symmetry is strongly broken during inflation thenon-Gaussianity parameter f_NL is generally large and negative.