Can primordial parity violation explain the observed cosmic birefringence?
Tomohiro Fujita, Y. Minami, Maresuke Shiraishi, Shuichiro Yokoyama
Abstract
Recently, the cross-correlation between $E$- and $B$-mode polarization of the cosmic microwave background, which is well explained by cosmic birefringence with rotation angle $\ensuremath{\beta}\ensuremath{\approx}0.3\text{ }\text{ }\mathrm{deg}$, has been found in cosmic microwave background polarization data. We carefully investigate the possibility of explaining the observed $EB$ correlation by the primordial chiral gravitational waves, which can be generated in the parity-violating theories in the primordial Universe. We found that the chiral gravitational wave scenario does not work due to the overproduction of the $BB$ autocorrelation, which far exceeds the observed one by SPTPol and POLARBEAR.