THE CHIRAL U(1) SYMMETRY IN LATTICE QCD WITH WILSON FERMIONS

The properties of singlet flavor chiral symmetry of lattice QCD with W ilson fermions are analyzed. We show that a suitable U (1) axial curre nt can be defined, satisfying, in the continuum limit, the Adler-Bell- Jackiw anomaly. Moreover, the renormalization properties of composite operators which appear in U(1) chiral Ward identities are discussed. F inally, starting from the renormalized Ward identities for the axial U (1) current, we analyze a definition of topological susceptibility sui table for nonperturbative studies and discuss preliminary numerical re sults.