Statistical Anisotropies in Gravitational Waves in Solid Inflation

TL;DR

This paper investigates statistical anisotropies in scalar and tensor perturbations within solid inflation, revealing unique features in their correlations and angular patterns that could influence CMB observations.

Contribution

It provides the first detailed calculation of anisotropic scalar and tensor power spectra and their cross-correlations in solid inflation, highlighting novel angular dependencies.

Findings

Tensor-scalar cross-correlation can be positive or negative.

Tensor power spectrum shows significant quadrupole and octopole contributions.

Anisotropies affect CMB TT and TB spectra more than scalar spectra.

Abstract

Solid inflation can support a long period of anisotropic inflation. We calculate the statistical anisotropies in the scalar and tensor power spectra and their cross-correlation in anisotropic solid inflation. The tensor-scalar cross-correlation can either be positive or negative, which impacts the statistical anisotropies of the TT and TB spectra in CMB map more significantly compared with the tensor self-correlation. The tensor power spectrum contains potentially comparable contributions from quadrupole and octopole angular patterns, which is different from the power spectra of scalar, the cross-correlation or the scalar bispectrum, where the quadrupole type statistical anisotropy dominates over octopole.