Shape of the inflaton potential and the efficiency of the universe heating

TL;DR

This paper demonstrates that the shape of the inflaton potential significantly influences the universe's heating efficiency, with non-harmonic oscillations greatly enhancing particle production and resulting in higher post-inflation temperatures.

Contribution

It introduces a new perspective on how the inflaton potential shape affects reheating, highlighting the importance of the approach to equilibrium beyond parametric resonance.

Findings

Non-harmonic inflaton oscillations increase particle production by several orders of magnitude.

The inflaton potential shape can be modified to enhance reheating without disrupting inflation.

Higher universe temperatures are achieved with step-function-like inflaton oscillations.

Abstract

It is shown that the efficiency of the universe heating by an inflaton field depends not only on the possible presence of parametric resonance in the production of scalar particles but also strongly depends on the character of the inflaton approach to its mechanical equilibrium point. In particular, when the inflaton oscillations deviate from pure harmonic ones toward a succession of step functions, the production probability rises by several orders of magnitude. This in turn leads to a much higher temperature of the universe after the inflaton decay, in comparison to the harmonic case. An example of the inflaton potential is presented which creates a proper modification of the evolution of the inflaton toward equilibrium and does not destroy the nice features of inflation.