Cosmological CPT violating effect on CMB polarization

TL;DR

This paper investigates how a cosmological CPT violation caused by a dark energy scalar field affects CMB polarization, deriving rotation formulas and estimating correction magnitudes in dark energy models.

Contribution

It provides a fully relativistic derivation of the CMB polarization rotation angle including spatial fluctuation corrections, advancing analysis methods for cosmological CPT violation.

Findings

Derived general relativistic rotation formulas for CMB polarization

Included spatial fluctuation corrections in the rotation angle

Estimated correction magnitudes in dynamical dark energy models

Abstract

A dark energy scalar (or a function of the Ricci scalar) coupled with the derivative to the matter fields will violate the $CPT$ symmetry during the expansion of the Universe. This type of cosmological $CPT$ violation helps to generate the baryon number asymmetry and gives rise to the rotation of the photon polarization which can be measured in the astrophysical and cosmological observations, especially the experiments of the cosmic microwave background radiation. In this paper, we derive the rotation angle in a fully general relativistic way and present the rotation formulas used for the cosmic microwave background data analysis. Our formulas include the corrections from the spatial fluctuations of the scalar field. We also estimate the magnitude of these corrections in a class of dynamical dark energy models for quintessential baryo/leptogenesis.