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. 55⁰. 82^ (random) 0. 5^ (systematic) using QUaD's 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range 200<<2000, consistent with null, and constrain Lorentz-violating interactions to <210^-43 GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.