Anomalous CMB polarization and gravitational chirality

Abstract

We consider the possibility that gravity breaks parity, with left and right handed gravitons coupling to matter with a different Newton's constant and show that this would affect their zero-point vacuum fluctuations during inflation. Should there be a cosmic background of gravity waves, the effect would translate into anomalous CMB polarization. Non-vanishing TB (and EB) polarization components emerge, revealing interesting experimental targets. Indeed if reasonable chirality is present a TB measurement would provide the easiest way to detect a gravitational wave background. We speculate on the theoretical implications of such an observation.

Figures (1)

• Figure 1: Tensor contribution to the $TB$ (solid, black), $BB$ (dashed, red), and $EB$ (dotted, blue) spectra for a standard $\Lambda$CDM model with tensor to scalar ratio $r=0.1$ and chirality parameter $\gamma = 10$.