# Searching for Fossil Fields in the Gravity Sector

## TL;DR

This paper explores how anisotropies in the tensor spectrum, caused by extra fields during inflation, can reveal new physics through their signatures in CMB B-modes and gravitational wave detectors.

## Contribution

It analyzes the impact of additional fields on tensor anisotropies and their potential to detect non-Gaussianities and break consistency relations in inflation models.

## Key findings

- Tensor quadrupolar anisotropy encodes information on squeezed tensor non-Gaussianities.
- Anisotropies provide a new probe for physics beyond the single-field inflation paradigm.
- Detectable signatures in CMB, interferometers, and pulsar timing arrays.

## Abstract

Evidence for the presence of extra fields during inflation may be found in the anisotropies of the scalar and tensor spectra across a vast range of scales. Indeed, beyond the single-field slow-roll paradigm, a long tensor mode can modulate the power spectrum inducing a sizable quadrupolar anisotropy. We investigate how this dynamics plays out for the tensor two-point correlator. The resulting quadrupole stores information on squeezed tensor non-Gaussianities, specifically those sourced by the extra field content and responsible for the breaking of so-called consistency relations. We underscore the potential of anisotropies as a probe of new physics: testable at CMB scales through the detection of B-modes, they are accessible at smaller scales via interferometers and pulsar timing arrays.