Plateau inflation is an experimentally consistent framework in which the scale of can be kept relatively low. Close to edge plateau, scalar perturbations are subject a strong tachyonic instability. Tachyonic preheating realized when, after inflation, oscillating inflaton repeatedly re-enters plateau. We develop analytic theory this process and expand linear approach by including backreaction be...

Abstract Recently, the problem of unitarity violation during preheating stage Higgs inflation with a large non-minimal coupling has been much discussed in literature. We point out that this can be translated into strong for dimensionless effective coupling, and existence these problems is highly dependent on choice higher-dimensional operators because they significantly change background dynami...