Linear Relations Among Normal-Product Fields

Abstract
General equations of motion are derived for normal-product fields within Zimmermann's formulation of renormalized perturbation theory. The equations of motion and Zimmermann identities relating normal products of different degree are shown to exhaust the linear relations among composite fields. An enlarged class of Ward-identity anomalies is discussed briefly, with specific reference to the breakdown of strict partial conservation of axial-vector current in a nonlinear σ model.