Restoring the sting to metric preheating - art. no. 061302

The relative growth of field and metric perturbations during preheating is sensitive to initial conditions set in the preceding inflationary phase. Re cent work suggests this may protect super-Hubble metric perturbations from resonant amplification during preheating. We show that this possibility is fragile and sensitive to the specific form of the interactions between the inflaton and other fields. The suppression is naturally absent in two class es of preheating in which either: (1) the vacua of the noninflaton fields d uring inflation are deformed away from the origin; or (2) the effective mas ses of noninflaton fields during inflation are small but during preheating are large. Unlike the simple toy model of a g(2)phi(2)chi(2) coupling, most realistic panicle physics models contain these other features. Moreover. t hey generically lead to both adiabatic and isocurvature modes and non-Gauss ian scars on super-Hubble scales. Large-scale coherent magnetic fields may also appear naturally.