Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter

We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment’s second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of cosmic microwave background photons. We measure the rotation angle due to such a possible “cosmological birefringence” to be $0.55°\pm 0.82°$ (random) $\pm 0.5°$ (systematic) using QUaD’s 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range $200<\ell <2000$, consistent with null, and constrain Lorentz-violating interactions to $<2\times {10}^{-43}\mathrm{GeV}$ (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.

Figure 1

$\Delta \alpha$ measured from QUaD 150 GHz TB and EB spectra; histogram of simulations and red line for data. The histogram does not account for systematic error. The dotted line indicates total uncertainty assuming a Gaussian 0.5° systematic error.

Figure 2

150 GHz $\Delta \alpha$ per–band power derived from the EB spectrum. Note that in practice these points are combined before the final transformation to $\Delta \alpha$—the purpose of this plot is to give a visual representation of the relative uncertainties across the band powers.