Inflationary models in $f(R,T)$ gravity: Constraints from $Planck$, BICEP/$Keck$, and Atacama

TL;DR

This paper investigates inflationary models within $f(R,T)$ gravity, analyzing their compatibility with recent cosmological data from Planck, BICEP/Keck, and other surveys, and identifies viable parameter spaces.

Contribution

It introduces and evaluates specific inflationary models in $f(R,T)$ gravity, comparing their predictions with current observational constraints.

Findings

Certain models fit within current observational bounds.

Predictions for $n_s$, $r$, and $n_{sk}$ are consistent with data.

Viable parameter spaces are identified for the models.

Abstract

The advent of high-precision cosmological observations has challenged many traditional inflationary models. Data from $Planck$ 2018 along with the BICEP/$Keck$ 2018 result have already ruled out most of the established models by placing tight constraints on the tensor-to-scalar ratio $r$. Upcoming missions like LiteBIRD & CMB-S4 are expected to impose an even more stringent bound on $r$ , potentially excluding further models from the viable landscape. In this evolving observational context, modified gravity theories offer a promising way to reconcile inflationary models with data. In this work, we explore several inflationary models, namely mutated hilltop inflation, D-brane inflation, and Woods-Saxon inflation, within the framework of $f(R, T)$ gravity. The cosmological observable parameters, viz. scalar spectral tilt $n_s$, tensor-to-scalar ratio $r$, and running of scalar spectral index $n_{sk}$ are estimated for the three models, and their trajectories are plotted in the $n_s-r$ plane. The model results are evaluated in light of the $Planck$, BICEP/$Keck$, DESI DR2, and ACT DR6 data. We observe that for a certain model parameter space, these potentials are viable within the current observational bounds.