Reheating Temperature and Inflaton Mass Bounds from Thermalization After Inflation

TL;DR

This paper investigates the thermalization process after inflation, showing how it affects bounds on reheating temperature and inflaton mass, with implications for the universe's thermal history and constraints from gravitino production.

Contribution

It highlights the importance of considering the full decay spectrum and delay in thermalization, providing new bounds on reheating temperature and inflaton mass in inflation models.

Findings

Reheating temperature bounds can be raised to 10^{12} GeV.

Thermalization before nucleosynthesis imposes inflaton mass limits.

Thermalization before electroweak transition is challenging in realistic models.

Abstract

We consider the conditions for the decay products of perturbative inflaton decay to thermalize. The importance of considering the full spectrum of inflaton decay products in the thermalization process is emphasized. It is shown that the delay between the end of inflaton decay and thermalization allows the thermal gravitino upper bound on the reheating temperature to be raised from 10^{8} GeV to as much as 10^{12} GeV in realistic inflation models. Requiring that thermalization occurs before nucleosynthesis imposes an upper bound on the inflaton mass as a function of the reheating temperature, m_{S} < 10^{10} (T_{R}/1 GeV)^{7/9} GeV. It is also shown that even in realistic inflation models with relatively large reheating temperatures, it is non-trivial to have thermalization before the electroweak phase transition temperature. Therefore the thermal history of the Universe is very sensitive to details of the inflation model.