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arXiv 2007.05915hep-thcond-mat.str-el
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离散θ角、对称性和反常

Discrete Theta Angles, Symmetries and Anomalies

Po-Shen Hsin, Ho Tat Lam

摘要:

不同维度的规范理论经常承认离散的θ角,这是由于用一个额外的对称保护拓扑(SPT)相来衡量一个全局对称而产生的。通过将规范理论与拓扑量子场论耦合,讨论了整体对称性和t Hooft反常如何依赖于离散θ角。我们观察到,测量阿贝尔子群对称性,参与对称性扩展,与一个额外的SPT阶段导致一个新的理论与紧急阿贝尔对称性,也参与了对称性扩展。规范理论的对称性扩展是由SPT相位产生的离散θ角控制的。我们发现,离散的θ角可以导致$SU(N),SU(N)/\mathbb{Z}_k$或$SO(N)$规范群以及各种3d和2d规范理论的4d QCD的两群对称性。

英文摘要:

Gauge theories in various dimensions often admit discrete theta angles, that arise from gauging a global symmetry with an additional symmetry protected topological (SPT) phase. We discuss how the global symmetry and 't Hooft anomaly depends on the discrete theta angles by coupling the gauge theory to a topological quantum field theory (TQFT). We observe that gauging an Abelian subgroup symmetry, that participates in symmetry extension, with an additional SPT phase leads to a new theory with an emergent Abelian symmetry that also participates in a symmetry extension. The symmetry extension of the gauge theory is controlled by the discrete theta angle which comes from the SPT phase. We find that discrete theta angles can lead to two-group symmetry in 4d QCD with $SU(N),SU(N)/\mathbb{Z}_k$ or $SO(N)$ gauge groups as well as various 3d and 2d gauge theories.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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