CMB B-mode auto-bispectrum produced by primordial gravitational waves

Abstract

Gravitational waves from inflation induce polarization patterns in the cosmic microwave background (CMB). It is known that there are only two types of non-Gaussianities of the gravitaional waves in the most general scalar field theories having second-order field equations. One originates from the inherent non-Gaussianity in general relativity, and the other from a derivative coupling between the Einstein tensor and a kinetic term of the scalar field. We calculate polarization bispectra induced by these non-Gaussianities by transforming them into separable forms by virtue of the Laplace transformation. It is shown that future experiments can detect only the new one if the latter coupling parameter takes an extremely large value, which, however, does not cotradict the current observational data.

10 pages, 6 figures

References in corpus (5)

• Planck 2015 results. XIII. Cosmological parameters
• A Joint Analysis of BICEP2/Keck Array and Planck Data
• Planck 2015 results. XVII. Constraints on primordial non-Gaussianity
• The shape of primordial non-Gaussianity and the CMB bispectrum
• The Odd-Parity CMB Bispectrum

Cited by in corpus (7)

• Horndeski theory and beyond: a review
• Tensor Non-Gaussianity Search: Current Status and Future Prospects
• Squeezed tensor non-Gaussianity in non-attractor inflation
• Primordial tensor non-Gaussianities from general single-field inflation with non-Bunch-Davies initial states
• Primordial non-Gaussianities of scalar and tensor perturbations in general bounce cosmology: Evading the no-go theorem
• B-Mode auto-bispectrum due to matter bounce
• Constraining graviton non-Gaussianity through the CMB bispectra