Fast-roll solutions from two scalar fields inflation

TL;DR

This paper derives analytic solutions for hybrid inflation models in the fast-roll regime with flat potentials, providing insights into their cosmological behavior and expanding the understanding beyond traditional slow-roll approximations.

Contribution

It introduces analytic solutions for hybrid inflation models in the fast-roll regime, extending the theoretical framework beyond slow-roll approximations.

Findings

Derived exact solutions for hybrid inflation in fast-roll regime.

Analyzed cosmological parameters like Hubble and equation of state.

Provided insights into inflation dynamics with flat potentials.

Abstract

One common approach for cosmic inflation consists in couple Einstein's gravity with a scalar field, often referred to inflaton field. In order to derive analytic simple scenarios, we usually work in the {\it slow-roll} regime. In such an approximation one considers the scalar field potentials to be nearly flat. It is possible to directly generalize such an approach for hybrid inflationary models, where the inflaton sector is composed of two or more scalar fields. However, the Friedmann equations and the equations of motion for such hybrid models are often hard to be analytically solved. Another recent path to describe cosmic inflation is through the so-called {\it fast-roll} regime, where one considers exactly flat potentials. Our purpose in this work is to obtain solutions for a hybrid inflaton model in the fast-roll regime. Cosmological interpretations through the behavior of Hubble, slow-roll, and equation of state parameters are also presented.