Primordial spectra from sudden turning trajectory

Abstract

Effects of heavy fields on primordial spectra of curvature perturbationsare discussed in inflationary models with a sudden turning trajectory.When heavy fields are excited after the sudden turn and oscillate aroundthe bottom of the potential, the following two effects are genericallyinduced: deformation of the inflationary background spacetime andconversion interactions between adiabatic and isocurvatureperturbations, both of which can affect the primordial densityperturbations. In this paper, we calculate primordial spectra ininflationary models with sudden turning potentials taking into accountboth of the two effects appropriately. We find that there are somenon-trivial correlations between the two effects in the power spectrumand, as a consequence, the primordial scalar power spectrum has a peakaround the scale exiting the horizon at the turn. Though both effectscan induce parametric resonance amplifications, they are shown to becanceled out for the case with the canonical kinetic terms. The peakfeature and the scale dependence of bispectra are also discussed.