Primordial spectra from sudden turning trajectory

TL;DR

This paper investigates how sudden turns in inflationary trajectories, involving heavy fields, influence primordial spectra, revealing a peak in the power spectrum and discussing potential resonance effects and bispectrum features.

Contribution

It provides a comprehensive calculation of primordial spectra considering both background deformation and perturbation conversion effects during sudden turns.

Findings

Primordial power spectrum exhibits a peak at the horizon exit scale.

Cancellation of parametric resonance effects in models with canonical kinetic terms.

Discussion of scale dependence in bispectra related to the turn.

Abstract

Effects of heavy fields on primordial spectra of curvature perturbations are discussed in inflationary models with a sudden turning trajectory. When heavy fields are excited after the sudden turn and oscillate around the bottom of the potential, the following two effects are generically induced: deformation of the inflationary background spacetime and conversion interactions between adiabatic and isocurvature perturbations, both of which can affect the primordial density perturbations. In this paper, we calculate primordial spectra in inflationary models with sudden turning potentials taking into account both of the two effects appropriately. We find that there are some non-trivial correlations between the two effects in the power spectrum and, as a consequence, the primordial scalar power spectrum has a peak around the scale exiting the horizon at the turn. Though both effects can induce parametric resonance amplifications, they are shown to be canceled out for the case with the canonical kinetic terms. The peak feature and the scale dependence of bispectra are also discussed.