Boltzmann equations for preheating

TL;DR

This paper derives quantum Boltzmann equations for preheating, highlighting the importance of pair correlations and showing that collisions suppress particle number growth early on.

Contribution

It introduces a formalism incorporating pair correlations into Boltzmann equations for preheating, with numerical analysis of collisional effects.

Findings

Pair correlations mediate particle production.

Collisions suppress early particle number growth.

Numerical solutions confirm collisional suppression.

Abstract

We derive quantum Boltzmann equations for preheating by means of the density matrix formalism, which account for both the non-adiabatic particle production and the leading collisional processes between the produced particles. In so doing, we illustrate the pivotal role played by pair correlations in mediating the particle production. In addition, by numerically solving the relevant system of Boltzmann equations, we demonstrate that collisional processes lead to a suppression of the growth of the number density even at the very early stages of preheating.