Probing CPT violation with CMB polarization measurements

The electrodynamics modified by the Chern-Simons term Lcs similar to p(mu)A(nu)(F) over tilde (mu nu) with a non-vanishing p(mu) violates the Charge-Parity-Time Reversal symmetry (CPT) and rotates the linear polarizations of the propagating Cosmic Microwave Background (CMB) photons. In this Letter we measure the rotation angle Delta alpha by performing a global analysis on the current CMB polarization measurements from the five-year Wilkinson Microwave Anisotropy Probe (WMAP5), BOOMERanG 2003 (B03), BICEP and QUaD using a Markov Chain Monte Carlo method. Neglecting the systematic errors of these experiments, we find that the results from WMAP5, B03 and BICEP all are consistent and their combination gives Delta alpha = -2.62 +/- 0.87 deg (68% C.L.), indicating a 3 sigma detection of the CPT violation. The QUaD data alone gives Delta alpha = 0.59 +/- 0.42 deg (68% C.L.) which has an opposite sign for the central value and smaller error bar compared to that obtained from WMAP5, B03 and BICEP. When combining all the polarization data together, we find Delta alpha = 0.09 +/- 0.36 deg (68% C.L.) which significantly improves the previous constraint on Delta alpha and test the validity of the fundamental CPT symmetry at a higher level. (C) 2010 Elsevier B.V. All rights reserved.