Boundary conditions and anomalies of conformal field theories in 1+1 dimensions

Fuente: arXiv
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Main Authors: Li, Linhao, Hsieh, Chang-Tse, Yao, Yuan, Oshikawa, Masaki
Format: Preprint
Published: 2022
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_version_ 1866929416771207168
author Li, Linhao
Hsieh, Chang-Tse
Yao, Yuan
Oshikawa, Masaki
author_facet Li, Linhao
Hsieh, Chang-Tse
Yao, Yuan
Oshikawa, Masaki
contents We study a relationship between conformally invariant boundary conditions and anomalies of conformal field theories (CFTs) in 1+1 dimensions. For a given CFT with a global symmetry, we consider symmetric gapping potentials which are relevant perturbations to the CFT. If a gapping potential is introduced only in a subregion of the system, it provides a certain boundary condition to the CFT. From this equivalence, if there exists a Cardy boundary state which is invariant under a symmetry, then the CFT can be gapped with a unique ground state by adding the corresponding gapping potential. This means that the symmetry of the CFT is anomaly free. Using this approach, we systematically deduce the anomaly-free conditions for various types of CFTs with several different symmetries. They include the free compact boson theory, Wess-Zumino-Witten models, and unitary minimal models. When the symmetry of the CFT is anomalous, it implies a Lieb-Schultz-Mattis type ingappability of the system. Our results are consistent with, where available, known results in the literature. Moreover, we extend the discussion to other symmetries including spin groups and generalized time-reversal symmetries.
format Preprint
id arxiv_https___arxiv_org_abs_2205_11190
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Boundary conditions and anomalies of conformal field theories in 1+1 dimensions
Li, Linhao
Hsieh, Chang-Tse
Yao, Yuan
Oshikawa, Masaki
High Energy Physics - Theory
Statistical Mechanics
Mathematical Physics
We study a relationship between conformally invariant boundary conditions and anomalies of conformal field theories (CFTs) in 1+1 dimensions. For a given CFT with a global symmetry, we consider symmetric gapping potentials which are relevant perturbations to the CFT. If a gapping potential is introduced only in a subregion of the system, it provides a certain boundary condition to the CFT. From this equivalence, if there exists a Cardy boundary state which is invariant under a symmetry, then the CFT can be gapped with a unique ground state by adding the corresponding gapping potential. This means that the symmetry of the CFT is anomaly free. Using this approach, we systematically deduce the anomaly-free conditions for various types of CFTs with several different symmetries. They include the free compact boson theory, Wess-Zumino-Witten models, and unitary minimal models. When the symmetry of the CFT is anomalous, it implies a Lieb-Schultz-Mattis type ingappability of the system. Our results are consistent with, where available, known results in the literature. Moreover, we extend the discussion to other symmetries including spin groups and generalized time-reversal symmetries.
title Boundary conditions and anomalies of conformal field theories in 1+1 dimensions
topic High Energy Physics - Theory
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2205.11190