Constraints on CPT violation from WMAP three year polarization data: a wavelet analysis

TL;DR

This paper uses wavelet analysis of WMAP data to search for parity-violating signals indicating CPT violation, setting tighter limits on photon rotation angle and finding no significant evidence for such effects.

Contribution

It introduces a wavelet-based method to constrain CPT violation in the CMB polarization data, improving previous limits on cosmological birefringence.

Findings

Set a tighter limit on the CMB photon rotation angle:   at 1 level.

Results are consistent with no CPT violation or parity violation.

Wavelet analysis enhances sensitivity to potential parity-violating signals.

Abstract

We perform a wavelet analysis of the temperature and polarization maps of the Cosmic Microwave Background (CMB) delivered by the WMAP experiment in search for a parity violating signal. Such a signal could be seeded by new physics beyond the standard model, for which the Lorentz and CPT symmetries may not hold. Under these circumstances, the linear polarization direction of a CMB photon may get rotated during its cosmological journey, a phenomenon also called cosmological birefringence. Recently, Feng et al. have analyzed a subset the WMAP and BOOMERanG 2003 angular power spectra of the CMB, deriving a constraint that mildly favors a non zero rotation. By using wavelet transforms we set a tighter limit on the CMB photon rotation angle \Delta\alpha= -2.5 \pm 3.0 (\Delta\alpha= -2.5 \pm 6.0) at the one (two) \sigma level, consistent with a null detection.