Wu, E.Y.S.Ade, P.Bowden, M.Brown, M.L.Cahill, G.Castro, P.G.Church, S.Culverhouse, T.Ganga, K.Gear, W.K.Gupta, S.Hinderks, J.Kovac, JohnLange, A.E.Leitch, E.Melhusish, S.J.Memari, Y.Murphy, J.A.Orlando, A.Piccirillo, L.Pryke, C.Rajguru, N.Rusholme, B.Schwarz, R.O'Sullivan, C.Taylor, A.N.Thompson, K.L.Turner, A.H.Zemcov, M.Bock, J.Friedman, R B2013-04-092009Wu, E. Y.S., P. Ade, J. Bock, M. Bowden, M.L. Brown, G. Cahill, P.G. Castro, et al. 2009. Parity violation constraints using cosmic microwave background polarization spectra from 2006 and 2007 observations by the QUaD polarimeter. Physical Review Letters 102(16):161302.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:10520826We 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 \(0.55^{\circ} \pm 0.82^{\circ}\) (random) \(\pm 0.5^{\circ}\) (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\(^ {-43}\) GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.en-USJournal Article2013-04-0910.1103/PhysRevLett.102.161302