Quantum interference in gravitational particle production

TL;DR

This paper explains unexplained fluctuations in gravitational particle production spectra by identifying quantum interference effects and provides analytic formulas for accurate amplitude calculations during inflation.

Contribution

It introduces a new analytic approach to account for quantum interference in gravitational particle production during inflation.

Findings

Interference causes spectral fluctuations in particle production.

Analytic formulas accurately model production amplitudes.

Results clarify the role of quantum effects in early universe particle creation.

Abstract

Previous numerical investigations of gravitational particle production during the coherent oscillation period of inflation displayed unexplained fluctuations in the spectral density of the produced particles. We argue that these features are due to the quantum interference of the coherent scattering reactions that produce the particles. We provide accurate analytic formulae to compute the particle production amplitude for a conformally-coupled scalar field, including the interference effect in the kinematic region where the production can be interpreted as inflaton scattering into scalar final states via graviton exchange.