Quantum theory of fermion production after inflation

TL;DR

This paper demonstrates that quantum effects significantly boost fermion production after inflation, leading to rapid thermalization and turbulent regimes, with implications for early universe physics and heavy-ion collisions.

Contribution

It reveals a nonperturbative quantum mechanism that enhances fermion production during preheating, surpassing classical predictions and involving rescattering of inflaton quanta.

Findings

Fermions approach a thermal infrared distribution rapidly.

Inflaton enters a turbulent scaling regime.

Quantum effects dramatically increase fermion production.

Abstract

We show that quantum effects dramatically enhance the production of fermions following preheating after inflation in the early Universe in the presence of high excitations of bosonic quanta. As a consequence fermions rapidly approach a quasistationary distribution with a thermal occupancy in the infrared, while the inflaton enters a turbulent scaling regime. The failure of standard semiclassical descriptions based on the Dirac equation with a homogeneous background field is caused by nonperturbatively high boson occupation numbers. During preheating the inflaton occupation number increases, thus leading to a dynamical mechanism for the enhanced production of fermions from the rescattering of the inflaton quanta. We comment on related phenomena in heavy-ion collisions for the production of quark matter fields from highly occupied gauge bosons.