Spin-Cobordisms, Surgeries and Fermionic Modular Bootstrap

Jun 30, 2021
86 pages
Published in:
  • Commun.Math.Phys. 401 (2023) 3, 3169-3245
  • Published: May 19, 2023
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Abstract: (Springer)
We consider general fermionic quantum field theories with a global finite group symmetry G, focusing on the case of 2 dimensions and torus spacetime. The modular transformation properties of the family of partition functions with different backgrounds are determined by the ’t Hooft anomaly of G and fermion parity. For a general possibly non-abelian G we provide a method to determine the modular transformations directly from the bulk 3d invertible topological quantum field theory (iTQFT) corresponding to the anomaly by inflow. We also describe a method of evaluating the character map from the real representation ring of G to the group which classifies anomalies. Physically the value of the map is given by the anomaly of free fermions in a given representation. We assume classification of the anomalies/iTQFTs by spin-cobordisms. As a byproduct, for all abelian symmetry groups G, we provide explicit combinatorial expressions for corresponding spin-bordism invariants in terms of surgery representation of arbitrary closed spin 3-manifolds. We work out the case of G=Z2G={\mathbb {Z}}_2 in detail, and, as an application, we consider the constraints that ’t Hooft anomaly puts on the spectrum of the infrared conformal field theory.
Note:
  • 86 pages, 27 figures. v2: minor corrections
  • bootstrap: modular
  • anomaly
  • field theory: topological
  • transformation: modular
  • fermion: field theory
  • spin
  • kink
  • crossing
  • space-time: torus
  • partition function