Quasi Scale-Invariant Inflationary Attractors

TL;DR

This paper demonstrates that a broad class of quasi scale-invariant inflationary models, derived from quadratic gravity with quantum corrections, produce consistent predictions for inflationary observables, forming a new attractor family distinct from known models.

Contribution

It introduces a family of quasi scale-invariant inflationary models with a common attractor behavior, linking Jordan frame models to Einstein frame potentials, and aligns with current observational data.

Findings

Models predict a specific tensor-to-scalar ratio and spectral index relation.

Quantum corrections in quadratic gravity support viable inflation.

The family of models is distinct from $oldsymbol{ ext{alpha}}$-attractors.

Abstract

We show that pure quadratic gravity with quantum loop corrections yields a viable inflationary scenario. We also show that a large family of models in the Jordan frame, with softly-broken scale invariance, corresponds to the same theory with linear inflaton potential in the Einstein frame. It follows that all these quasi scale-invariant models have the same relation between the tensor-to-scalar ratio and the scalar spectral index, which is also consistent with the current data. Thus, they form a family of attractors, which is sharply distinct from the recently discovered $\alpha$-attractors of Kallosh, Linde et al.