High-Scale Inflation and the Tensor Tilt

TL;DR

This paper investigates how gravitational corrections during slow-roll inflation, specifically couplings to higher-curvature tensors, can modify the tensor tilt and violate the standard tensor consistency condition, offering a new observational signature.

Contribution

It introduces a novel correction to the tensor spectrum from Weyl tensor couplings, highlighting a potential violation of the tensor consistency condition in inflationary models.

Findings

Correction to tensor tilt due to Weyl tensor coupling

Violation of the tensor consistency condition

Consistent results from conformal perturbation theory

Abstract

In this paper, we explore a novel observational signature of gravitational corrections during slow-roll inflation. We study the coupling of the inflaton field to higher-curvature tensors in models with a minimal breaking of conformal symmetry. In that case, the most general correction to the tensor two-point function is captured by a coupling to the square of the Weyl tensor. We show that these scenarios lead to a correction to the tilt of the tensor power spectrum and hence a violation of the tensor consistency condition. We arrive at the same conclusion through an analysis in conformal perturbation theory.