Primordial tensor bispectra in $\mu$-CMB cross-correlations

Understand

Cross-correlations between Cosmic Microwave Background (CMB) temperature and polarization anisotropies and $\mu$-spectral distortions have been considered to measure (squeezed) primordial scalar bispectra in a range of scales inaccessible to primary CMB bispectra.

• In this work we address whether it is possible to constrain tensor non-Gaussianities with these cross-correlations.
• We find that only primordial tensor bispectra with statistical anisotropies leave distinct signatures, while isotropic tensor bispectra leave either vanishing or highly suppressed signatures.
• We discuss how the angular dependence of squeezed bispectra in terms of the short and long momenta determine the non-zero cross-correlations.