Circle compactification and 't Hooft anomaly

Abstract

Anomaly matching constrains low-energy physics of strongly-coupled field theories, but it is not useful at finite temperature due to contamination from high-energy states. The known exception is an 't Hooft anomaly involving one-form symmetries as in pure $SU(N)$ Yang-Mills theory at $\theta =\pi$. Recent development about large-$N$ volume independence, however, gives us a circumstantial evidence that 't Hooft anomalies can also remain under circle compactifications in some theories without one-form symmetries. We develop a systematic procedure for deriving an 't Hooft anomaly of the circle-compactified theory starting from the anomaly of the original uncompactified theory without one-form symmetries, where the twisted boundary condition for the compactified direction plays a pivotal role. As an application, we consider ${\mathbb{Z}}_N$-twisted $\mathbb{C}{P}^{N-1}$ sigma model and massless ${\mathbb{Z}}_N$-QCD, and compute their anomalies explicitly.

Comments: 22 pages; (v2) references updated, minor changes