ASI SponsorCabella, PaoloPaoloCabellaNatoli, PaoloPaoloNatoliSilk, JosephJosephSilk2020-09-172020-09-172007-01-01https://hdl.handle.net/20.500.13025/2018We perform a wavelet analysis of the temperature and polarization maps of the cosmic microwave background (CMB) delivered by the Wilkinson Microwave Anisotropy Probe 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 of the Wilkinson Microwave Anisotropy Probe and BOOMERanG 2003 angular power spectra of the CMB, deriving a constraint that mildly favors a nonzero rotation. By using wavelet transforms we set a tighter limit on the CMB photon rotation angle 2:5 3:0 ( 2:5 6:0) at the one (two) level, consistent with a null detection.Article Journal10.1103/PhysRevD.76.123014http://prd.aps.org/abstract/PRD/v76/i12/e12301454dcce098580fe1368eeb1a9