A SymTFT for Continuous Symmetries

A SymTFT for Continuous Symmetries

5 Nov 2024 | T. Daniel Brennan and Zhengdi Sun
This paper introduces a Symmetry TQFT (SymTFT) framework for continuous symmetries, extending the known approach for discrete symmetries. The SymTFT provides a way to encode both the global symmetries and their anomalies of a quantum field theory (QFT). The framework is applied to study $ U(1) $ global symmetries, including their anomalies and non-invertible chiral $ Q/Z $ symmetries in 4d theories. The paper also proposes a SymTFT for general continuous $ G^{(0)} $ global symmetries, where $ G $ is a continuous non-abelian Lie group. The SymTFT is constructed by associating a $ (d+1) $-dimensional TQFT with a $ d $-dimensional QFT, where the TQFT encodes the symmetries and their anomalies of the QFT. The TQFT is defined on a manifold $ Y_{d+1} = X_d \times [0,1] $, with the QFT on the boundary $ X_d $ and the TQFT on the interior. The TQFT includes topological operators that describe the possible topological symmetry operators in the QFT and their fusion, linking, and braiding. For $ U(1) $ global symmetries, the SymTFT is described by a Lagrangian involving a $ (p+1) $-form $ U(1) $ gauge field $ a_{p+1} $ and a $ (d-p-1) $-form R gauge field $ h_{d-p-1} $. The action is given by: $$ S_{U(1)} = \frac{i}{2\pi} \int d a_{p+1} \wedge \widetilde{h}_{d-p-1} $$ This action is similar to the $ Z_N $ SymTFT, which is described by a BF theory. The $ U(1) $ SymTFT can be related to the $ Z_N $ SymTFT in the limit $ N \to \infty $, where $ N B_{d-p-1} \mapsto h_{d-p-1} $ and $ A_{p+1} \mapsto a_{p+1} $. The SymTFT includes topological operators such as Wilson lines $ W_n(\gamma) = e^{i n \oint a} $ and surface operators $ \mathcal{W}_\alpha(\Sigma) = e^{i \alpha \oint h} $, which have non-trivial braiding. The possible quiche boundary conditions are given by Dirichlet and Neumann boundary conditions, which fix either $ a_{p+1} $ or $ h_{d-p-1} $, respectively. The paper also discusses the anomalies ofThis paper introduces a Symmetry TQFT (SymTFT) framework for continuous symmetries, extending the known approach for discrete symmetries. The SymTFT provides a way to encode both the global symmetries and their anomalies of a quantum field theory (QFT). The framework is applied to study $ U(1) $ global symmetries, including their anomalies and non-invertible chiral $ Q/Z $ symmetries in 4d theories. The paper also proposes a SymTFT for general continuous $ G^{(0)} $ global symmetries, where $ G $ is a continuous non-abelian Lie group. The SymTFT is constructed by associating a $ (d+1) $-dimensional TQFT with a $ d $-dimensional QFT, where the TQFT encodes the symmetries and their anomalies of the QFT. The TQFT is defined on a manifold $ Y_{d+1} = X_d \times [0,1] $, with the QFT on the boundary $ X_d $ and the TQFT on the interior. The TQFT includes topological operators that describe the possible topological symmetry operators in the QFT and their fusion, linking, and braiding. For $ U(1) $ global symmetries, the SymTFT is described by a Lagrangian involving a $ (p+1) $-form $ U(1) $ gauge field $ a_{p+1} $ and a $ (d-p-1) $-form R gauge field $ h_{d-p-1} $. The action is given by: $$ S_{U(1)} = \frac{i}{2\pi} \int d a_{p+1} \wedge \widetilde{h}_{d-p-1} $$ This action is similar to the $ Z_N $ SymTFT, which is described by a BF theory. The $ U(1) $ SymTFT can be related to the $ Z_N $ SymTFT in the limit $ N \to \infty $, where $ N B_{d-p-1} \mapsto h_{d-p-1} $ and $ A_{p+1} \mapsto a_{p+1} $. The SymTFT includes topological operators such as Wilson lines $ W_n(\gamma) = e^{i n \oint a} $ and surface operators $ \mathcal{W}_\alpha(\Sigma) = e^{i \alpha \oint h} $, which have non-trivial braiding. The possible quiche boundary conditions are given by Dirichlet and Neumann boundary conditions, which fix either $ a_{p+1} $ or $ h_{d-p-1} $, respectively. The paper also discusses the anomalies of
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Understanding A SymTFT for continuous symmetries