Primordial power spectrum of tensor perturbations in Finsler spacetime

TL;DR

This paper explores how Finsler spacetime modifies gravitational waves and the primordial tensor power spectrum, revealing anisotropic effects and parity violation that impact cosmic microwave background correlations.

Contribution

It derives the perturbed gravitational field equations in Finsler spacetime and predicts unique anisotropic and parity-violating signatures in the primordial tensor power spectrum.

Findings

Finsler spacetime induces anisotropic effects in gravitational waves.

Parity violation leads to specific angular correlation patterns.

Numerical results show dependence of anisotropic effects on mode m.

Abstract

We first investigate the gravitational wave in the flat Finsler spacetime. In the Finslerian universe, we derive the perturbed gravitational field equation with tensor perturbations. The Finslerian background spacetime breaks rotational symmetry and induces parity violation. Then we obtain the modified primordial power spectrum of tensor perturbations. The parity violation feature requires that the anisotropic effect contributes to $TT,TE,EE,BB$ angular correlation coefficients with $l'=l+1$ and $TB,EB$ with $l'=l$. The numerical results show that the anisotropic contributions to angular correlation coefficients depend on $m$, and $TE$ and $ET$ angular correlation coefficients are different.