Momentum space entanglement of four fermion field theory

Momentum space entanglement of four fermion field theory is calculated from the Wilsonian effective action pertubatively using replica trick, local terms in low energy effective action are proved to be nonrelevant pertubatively, and nonlocal terms are the only source of entanglement between different momentum modes. The final result can be represented by a set of basketball Feynman diagrams with new Feynman rules proposed to interpret them.