PERTURBATION LAGRANGIAN THEORY FOR DIRAC FIELDS — WARD-TAKAHASHI IDENTITY AND CURRENT-ALGEBRA

摘要

In a class of Lagrangian field theories for Dirac episi1/2 partsicles, the BPH renormalization scheme provides a proof of the operator forms of Euler Lagrange equations of action, Roetl there theorem and Ward-Takahsshi identities. Time-ordered products for soma derivatives of Dirac fields can only be defined with special care in tens of Feywaan graphs. Current-algebra Ward-Tahahashi identities are obtained if derivative is invariant under the algebra;however, Schwinger terms are absent from these identities .