Constraints on non-canonical chaotic inflation from ACT DR6 and BICEP/Keck data

TL;DR

This paper constrains non-canonical chaotic inflation models using ACT DR6 and BICEP/Keck data, establishing bounds on model parameters and confirming the viability of certain inflation scenarios within observational limits.

Contribution

It provides the first precise numerical constraints on the non-canonical parameter and potential index in chaotic inflation models using comprehensive cosmological datasets.

Findings

Constraints on the non-canonical parameter $\alpha$ for specific potentials.

Number of e-foldings converges to approximately 54 without fine-tuning.

Non-standard mechanisms can revive excluded inflation models within observational bounds.

Abstract

In this study, we precisely evaluated the feasibility of the chaotic inflation model within a non-canonical kinetic framework. By applying the slow-roll approximation and imposing constraints on the equilateral non-Gaussianity $f_{\rm NL}^{\rm equil}$, we imposed constraints on the feasible range of the potential index $n$. We established physical bounds for the non-canonical parameter $\alpha$. To obtain precise parameter constraints, we solved the primordial perturbation equations numerically and conducted a rigorous MCMC analysis by using a comprehensive joint P-ACT-LB-BK18 dataset. For these potentials $n=1/3$, $2/3$, and $1$, our results respectively tightly limit $\alpha$ to the levels of $8.8^{+1.6}_{-2.8}$, $11.7^{+1.7}_{-2.6}$, and $16.4^{+3.7}_{-7.0}$, within the corresponding $1\sigma$ confidence intervals. Meanwhile, the required number of $e$-foldings naturally converges to $N \simeq 54$, without the need for fine-tuning. These findings confirm that non-standard mechanisms can resurrect excluded chaotic inflation models within the $1\sigma$ allowed regions of high-precision cosmological data.