Operator dimension parity fractionalization
摘要
Lorentz invariant quantum field theories (QFTs) with fermions in four spacetime dimensions (4D) have a ℤ4 symmetry provided there exists a basis of operators in the QFT where all operators have even operator dimension, d, including those with d > 4. The ℤ4 symmetry is the extension of operator dimension parity by fermion number parity. If the ℤ4 is anomaly-free, such QFTs can be related to 3D topological superconductors. Additionally, imposing the ℤ4 symmetry on the Standard Model effective field theory severely restricts the allowed processes that violate baryon and lepton numbers.