A review of Quintessential Inflation

TL;DR

This paper numerically analyzes gravitational particle production during Quintessential Inflation, showing high reheating temperatures and confirming that gravitational waves do not disrupt Big Bang Nucleosynthesis in these models.

Contribution

It provides the first detailed numerical computation of reheating temperatures in Lorentzian and $\alpha$-attractors Quintessential Inflation scenarios.

Findings

Reheating temperatures exceed 10^7 GeV in both models.

Heavy particle production is efficient despite expectations.

Gravitational wave over-production does not affect BBN.

Abstract

We compute numerically the reheating temperature due to the gravitational production of conformally coupled superheavy particles during the phase transition from the end of inflation to the beginning of kination in two different Quintessential Inflation (QI) scenarios, namely Lorentzian Quintessential Inflation (LQI) and $\alpha$-attractors in the context of Quintessential Inflation ($\alpha$-QI). Once these superheavy particles have been created, they must decay into lighter ones to form a relativistic plasma, whose energy density will eventually dominate the one of the inflaton field in order to reheat after inflation our universe with a very high temperature, in both cases greater than $10^7$ GeV, contrary to the usual belief that heavy masses suppress the particle production and, thus, lead to an inefficient reheating temperature. Finally, we will show that the over-production of Gravitational Waves (GWs) during this phase transition, when one deals with our models, does not disturb the Big Bang Nucleosynthesis (BBN) success.