New Exponential and Polynomial $\xi$-attractors

TL;DR

This paper introduces a new family of cosmological attractors with non-minimal gravity coupling, transforming into exponential and polynomial models that can fit various observational data.

Contribution

It presents a novel class of cosmological attractors with specific spectral index and tensor-to-scalar ratio properties, including a supergravity implementation.

Findings

Spectral index $n_s$ spans a broad range compatible with data.

Tensor-to-scalar ratio $r$ can approach zero for large $\xi$.

Models can match data from Planck, BICEP/Keck, ACT, SPT, and DESI.

Abstract

We introduce a new family of cosmological attractors with non-minimal coupling of gravity and non-canonical kinetic terms. In the Einstein frame, these models transform into a class of exponential and polynomial attractors with the spectral index $n_{s}$ spanning a broad range $1-2/N \leq n_{s} < 1-1/N$, and $r$ can decrease to zero in the limit $\xi \to \infty$. This is sufficient to match any combination of Planck, BICEP/Keck, ACT, SPT, and DESI data. We present a supergravity implementation of these models.