Reassessing constant-roll Warm Inflation

TL;DR

This paper investigates constant-roll dynamics within Warm Inflation, deriving conditions for sustained inflation and examining how different dissipative models affect thermal equilibrium and the viability of constant-roll scenarios.

Contribution

It extends the constant-roll inflation framework to Warm Inflation, identifying conditions for sustained inflation and analyzing the impact of dissipative coefficients on thermal equilibrium.

Findings

Certain dissipative models support constant-roll Warm Inflation.

Models with temperature-dependent dissipation can sustain constant-roll WI.

Some models fail to maintain thermal equilibrium under constant-roll conditions.

Abstract

Departing from standard slow-roll conditions is one way of putting the inflationary paradigm to test, and constraining the dynamics of the inflaton field with a constant-rate of roll of the inflaton field, a.k.a. the constant-roll scenario, is one way of exploring such deviation from the standard slow-roll dynamics. In this manuscript we explore such a possibility in a variant inflationary scenario, known as Warm Inflation. We construct and derive the conditions for having constant-roll WI models where inflation lasts at least for 60 $e-$folds, gracefully exits the constant-roll inflation phase, and maintains near thermal equilibrium of the system which is an essential feature of WI in the slow-roll regime. We show that while certain models of WI (the ones with dissipative coefficient as a function of temperature alone) can accommodate constant-roll dynamics, others (with dissipative coefficient as a function of temperature and the inflaton field both) fail to maintain thermal equilibrium once the constant-roll condition is imposed and hence cannot produce a constant-roll WI phase.