Towards general patterns of features in multi-field inflation

TL;DR

This paper develops a general formalism for multi-field inflation with curved trajectories, revealing that resonance effects cause oscillatory features in the power spectrum without slow-roll suppression.

Contribution

It introduces a comprehensive formalism using the mass basis for multi-field inflation and analyzes the impact of curved trajectories on the power spectrum.

Findings

Oscillatory features in the power spectrum due to resonance effects.

Resonance of heavy modes causes sinusoidal corrections in the logarithm of wavenumber.

Corrections occur without slow-roll suppression.

Abstract

We investigate the consequences of general curved trajectories in multi-field inflation. After setting up a completely general formalism using the mass basis, which naturally accommodates the notion of light and heavy modes, we study in detail the simple case of two successive turns in two-field system. We find the power spectrum of the curvature perturbation receives corrections that exhibit oscillatory features sinusoidal in the logarithm of the comoving wavenumber without slow-roll suppression. We show that this is because of the resonance of the heavy modes inside and outside the mass horizon.