Constant-roll warm inflation within Rastall gravity

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=Γ3H, where Γ 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 V0=0 and V0≠0. In this study, we focus on the effects of the theory parameter λ, CR parameter β, 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 2σ confidence level. Finally, we conclude that the CR technique produces significant changes in the early universe.

Keywords

• Modified gravity
• Warm inflation
• Constant-roll approximation