Odd-parity cosmic microwave background bispectrum
Measurement of the CMB bispectrum, or three-point correlation function, has now become one of the principle efforts in early-Universe cosmology. Here we show that there is an odd-parity component of the CMB bispectrum that has been hitherto unexplored. We argue that odd-parity temperature-polarization bispectra can arise, in principle, through weak lensing of the CMB by chiral gravitational waves or through cosmological birefringence, although the signals will be small even in the best-case scenarios. Measurement of these bispectra requires only modest modifications to the usual data-analysis algorithms. They may be useful as a consistency test in searches for the usual bispectrum and to search for surprises in the data.
Additional Information© 2011 American Physical Society. Received 21 October 2010; published 14 January 2011. M. K. is thankful for the support of the Miller Institute for Basic Research in Science at the University of California, Berkeley, where part of this work was completed. M. K. was supported at Caltech by DOE Grant No. DE-FG03-92-ER40701, NASA Grant No. NNX10AD04G, and the Gordon and Betty Moore Foundation. T. S. acknowledges support from the Swarnajayanti Grant, DST, India, and the visit to Caltech during which the work was initiated.
Published - Kamionkowski2011p12680Phys_Rev_D.pdf