Dec 3 – 6, 2019
KEK
Japan timezone

2d 't Hooft anomaly, orbifolding, and boundary states

Dec 4, 2019, 4:50 PM
15m
Kobayashi Hall, Kenkyu-Honkan bldg. 1F (KEK)

Kobayashi Hall, Kenkyu-Honkan bldg. 1F

KEK

Speaker

Dr Ken Kikuchi

Description

We study anomalies for a discrete internal global symmetry $G$ in two-dimensional conformal field theories based on twisted torus partition functions. The 't Hooft anomaly of $G$ can be seen from the noncommutativity of two symmetry lines inserted along the nontrivial circles of two-torus and we propose a criterion to detect the 't Hooft anomaly, which agrees with the truncated modular $S$-matrix approach as well as the cohomology classification. The obstruction for orbifolding has been recently interpreted as a mixed anomaly between $G$ and large diffeomorphisms. We clarify the relations among 't Hooft anomaly-free, orbifolding condition and invariant boundary state condition, focusing on Wess-Zumino-Witten models.

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