Testing CPT Symmetry with CMB Measurements

TL;DR

This study investigates CPT symmetry using CMB polarization data, finding a slight indication of violation with current measurements and projecting improved constraints with future Planck data.

Contribution

It provides the first combined analysis of BOOMERanG and WMAP3 data for CPT violation and forecasts Planck's enhanced sensitivity to polarization rotation.

Findings

WMAP3 data suggests a rotation angle of -6.2±3.8 degrees.

Planck will be able to measure the rotation angle with a precision of 0.057 degrees.

Results slightly increase the significance of CPT violation compared to previous studies.

Abstract

In this paper we study the possibility of testing \emph{CPT} symmetry with Cosmic Microwave Background (CMB) measurements. Working with an effective lagrangian of the photon with \emph{CPT} violation ${\cal L} \sim p_{\mu}A_{\nu}\tilde F^{\mu\nu}$ which causes the polarization vectors of the propagating CMB photons rotated, we determine the rotation angle $\Delta\alpha$ using the BOOMERanG 2003 and the WMAP3 angular power spectra. In this analysis we have included the newly released $TC$ and $GC$ ($l<450$) information of WMAP3 and found $\Delta\alpha=-6.2\pm3.8$ deg at $1\sigma$ confidence level. This result increases slightly the significance for the \emph{CPT} violation obtained in our previous paper (Feng \emph{et al.}, 2006) $\Delta\alpha=-6.0 \pm 4.0$ deg (1$\sigma$). Furthermore we examine the constraint on the rotation angle with the simulated Planck data. Our results show that the Planck will be sensitive to $\Delta \alpha$ at the level of 0.057 deg and able to test the \emph{CPT} symmetry with a higher precision.