New Constraints on Anisotropic Rotation of CMB Polarization
  The coupling of a scalar field to electromagnetic field via the Chern-Simons
term will rotate the polarization directions of the cosmic microwave background
radiation. The rotation angle which relies on the distribution of the scalar
field on the CMB sky is direction dependent. Such anisotropies will give rise
to new distortions to the power spectra of CMB polarization and it can be used
to probe the detailed physics of the scalar field. In this paper we use the
updated observational data to constrain the anisotropic rotation angle in a
model independent way. We find that the dominant effect of the anisotropic
rotation on CMB comes from its variance and it is constrained tightly by the
current data.
