Testing CPT Symmetry with CMB Measurements: Update after WMAP5

TL;DR

This paper updates the measurement of CPT symmetry violation using CMB polarization data, combining WMAP5 and BOOMERanG 2003 datasets to refine the rotation angle of polarization vectors.

Contribution

It provides a new combined analysis of WMAP5 and BOOMERanG 2003 data to improve constraints on CPT violation in the photon sector.

Findings

Measured rotation angle Δα = -2.6 ± 1.9 degrees.

Combined data yields more precise constraints than previous analysis.

Results are consistent with no CPT violation within uncertainties.

Abstract

In this Letter we update our previous result on the test of CPT symmetry with Cosmic Microwave Background (CMB) measurements. A CPT violating interaction in the photon sector ${\cal L}_{cs} \sim p_{\mu}A_{\nu}\tilde F^{\mu\nu}$ gives rise to a rotation of the polarization vectors of the propagating CMB photons. Recently the WMAP group used the newly released polarization data of WMAP5 to measure this rotation angle $\Delta\alpha$ and obtained $\Delta\alpha=-1.7\pm2.1$ deg ($1\sigma$). However, in their analysis the BOOMERanG 2003 data is not included. Here we revisit this issue by combining the full data of WMAP5 and BOOMERanG 2003 angular power spectra for the measurement of this rotation angle $\Delta\alpha$ and find that $\Delta\alpha=-2.6\pm1.9$ deg at a 68% confidence level.