Constant-roll Warm Inflation within Rastall Gravity

TL;DR

This paper explores constant-roll warm inflation within Rastall gravity, analyzing how model parameters affect inflationary observables and compatibility with recent cosmological data, revealing significant early universe effects.

Contribution

It introduces a novel approach to exact inflationary solutions in Rastall gravity using constant-roll warm inflation, incorporating dissipation effects and observational constraints.

Findings

Model parameters constrained by Planck and BICEP/Keck data.

Inflationary observables compatible within 2σ confidence level.

CR technique significantly impacts early universe dynamics.

Abstract

This research paper used a newly proposed strategy for finding the exact inflationary solutions to the Friedman equations in the context of Rastall theory of gravity (RTG), which is known as constant-roll warm inflation (CRWI). The dissipative effects produced during WI are studied by introducing a dissipation factor $Q=\frac{\Gamma}{3H}$, where $\Gamma$ is the coefficient of dissipation. We establish the model to evaluate the inflaton field, effective potential requires to produce inflation, and entropy density. These physical quantities lead to developing the important inflationary observables like scalar/tensor power spectrum, scalar spectral index, tensor-to-scalar ratio, and running of spectral-index for two choices of obtained potential that are $V_0=0$ and $V_0\neq0$. In this study, we focus on the effects of the theory parameter $\lambda$, CR parameter $\beta$, and dissipation factor $Q$ (under a high dissipative regime for which $Q=$constant) on inflation and are constrained to observe the compatibility of our model with Planck TT+lowP (2013), Planck TT, TE, EE+lowP (2015), Planck 2018 and BICEP/Keck 2021 bounds. The results are feasible and interesting up to the $2\sigma$ confidence level. Finally, we conclude that the CR technique produces significant changes in the early universe.