45 research outputs found
Parity violation in the CMB bispectrum by a rolling pseudoscalar
We investigate parity-violating signatures of temperature and polarization
bispectra of the cosmic microwave background (CMB) in an inflationary model
where a rolling pseudoscalar produces large equilateral tensor non-Gaussianity.
By a concrete computation based on full-sky formalism, it is shown that
resultant CMB bispectra have nonzero signals in both parity-even and parity-odd spaces, and are almost uncorrelated with usual scalar-mode equilateral
bispectra. These characteristic signatures and polarization information help to
detect such tensor non-Gaussianity. Use of both temperature and E-mode
bispectra potentially improves of the detectability with respect to an
analysis with temperature bispectrum alone. Considering B-mode bispectrum, the
signal-to-noise ratio may be able to increase by 3 orders of magnitude. We
present the uncertainties of a parameter depending on a coupling
constant and a rolling condition for the pseudoscalar expected in the and the proposed PRISM experiments.Comment: 19 pages, 5 figures. Accepted for publication in JCA