Cross-correlation of cosmological birefringence with CMB temperature
Theories for new particle and early-Universe physics abound with pseudo-Nambu-Goldstone fields that arise when global symmetries are spontaneously broken. The coupling of these fields to the Chern-Simons term of electromagnetism may give rise to cosmological birefringence (CB), a frequency-independent rotation of the linear polarization of photons as they propagate over cosmological distances. Inhomogeneities in the CB-inducing field may yield a rotation angle that varies across the sky. Here we note that such a spatially-varying birefringence may be correlated with the cosmic microwave background (CMB) temperature. We describe quintessence scenarios where this cross-correlation exists and other scenarios where the scalar field is simply a massless spectator field, in which case the cross-correlation does not exist. We discuss how the cross-correlation between CB-rotation angle and CMB temperature may be measured with CMB polarization. This measurement may improve the sensitivity to the CB signal, and it can help discriminate between different models of CB.
Additional Information© 2011 American Physical Society. Received 7 April 2011; published 5 August 2011. We thank C. Hirata for useful discussions. MK thanks the support of the Miller Institute for Basic Research in Science and the hospitality of the Department of Physics at the University of California, Berkeley, where part of this work was completed. This work was supported in part by NSF AST-0349213 at Dartmouth and by DoE DE-FG03-92-ER40701, NASA NNX10AD04G, and the Gordon and Betty Moore Foundation at Caltech.
Published - Caldwell2011p15524Phys_Rev_D.pdf