Pre-inflationary primordial perturbations

TL;DR

This paper explores how pre-inflationary phases, including bounces or superinflation, influence primordial perturbations and large-scale power suppression in the cosmic microwave background.

Contribution

It provides a universal formula for the primordial power spectrum considering multiple pre-inflationary phases using recursive Bogoliubov coefficients.

Findings

Pre-inflationary physics can significantly suppress large-scale power.

The derived formula applies to various pre-inflationary scenarios.

Large-scale power suppression depends on the specific pre-inflationary evolution.

Abstract

The large-scale power deficit in the cosmic microwave background fluctuations might be relevant with the physics of pre-inflation, a bounce, or a superinflationary phase preceding slow-roll inflation, which can provide a singular-free realization of inflation. We investigate the primordial perturbations from such pre-inflationary evolutions, which generally may consist of multiple phases with different background dynamics, and give a universal formula for the power spectrum of primordial perturbations in terms of the recursive Bogoliubov coefficients. We also apply our formula to corresponding cases and show how the intensity of large-scale power suppression is affected by the pre-inflationary physics.