From Equivalence Principles to Cosmology: Cosmic Polarization Rotation, CMB Observation, Neutrino Number Asymmetry, Lorentz Invariance and CPT

TL;DR

This paper reviews the connection between cosmic polarization rotation, equivalence principles, and fundamental physics, highlighting observational limits from CMB data and prospects for future measurements to test Lorentz invariance and CPT violation.

Contribution

It presents a comprehensive review of how pseudoscalar-photon interactions relate to cosmological polarization rotation and fundamental symmetries, incorporating recent observational constraints and future prospects.

Findings

WMAP limited polarization rotation to 0.1 rad

Pseudoscalar-photon interaction linked to neutrino asymmetry

Future PLANCK mission will improve measurement accuracy

Abstract

In this paper, we review the approach leading to cosmic polarization rotation observation and present the current status with an outlook. In the study of the relations among equivalence principles, we found that long-range pseudoscalar-photon interaction is allowed. Pseudoscalar-photon interaction would induce a rotation of linear polarization of electromagnetic wave propagating with cosmological/astrophysical distance. In 2002, DASI successfully observed the polarization of the cosmological microwave background radiation. In 2003, WMAP observed the correlation of polarization with temperature anisotropy at more than 10 sigma in the cosmological microwave background. From this high polarization-temperature correlation in WMAP observation, we put a limit of 0.1 rad on the rotation of linear polarization of cosmological microwave background (CMB) propagation. Pseudoscalar-photon interaction is proportional to the gradient of the pseudoscalar field. From phenomenological point of view, this gradient could be neutrino number asymmetry current, other density current, or a constant vector. In these situations, Lorentz invariance or CPT may or may not effectively be violated. In this paper, we review and compile various results. Better accuracy in CMB polarization observation is expected from PLANCK mission to be launched next year. A dedicated CMB polarization observer in the future would probe this fundamental issue more deeply.