$\theta =\pi$ in $SU(N)/{\mathbb{Z}}_N$ gauge theories

Ryuichiro Kitano, Takao Suyama, Norikazu Yamada

In $SU(N)$ gauge theory, it is argued recently that there exists a "mixed anomaly" between the CP symmetry and the 1-form ${\mathbb{Z}}_N$ symmetry at $\theta =\pi$, and the anomaly matching…