title: How to derotate the cosmic microwave background polarization.
abstract: If the linear polarization of the cosmic microwave background is rotated in a frequency-independent manner as it propagates from the surface of last scatter, it may introduce a B-mode polarization. Here I show that measurement of higher-order TE, EE, EB, and TB correlations induced by this rotation can be used to reconstruct the rotation angle as a function of position on the sky. This technique can be used to distinguish primordial B modes from those induced by rotation. The effects of rotation can be distinguished geometrically from similar effects due to cosmic shear.
authors.affiliation: California Institute of Technology, Mail Code 130-33, Pasadena, California 91125, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Kamionkowski