Spectral function sum rules in quantum chromodynamics (II). Flavour components of the electromagnetic current

Abstract

Sum rules of the algebra of currents of the type of the Das, Mathur, Okubo sum rule are reconsidered in the light of quantum chromodynamics (QCD). These sum rules are replaced by new finite-energy sum rules which equate differences of definite integrals of the various flavour components of the electromagnetic spectral function to functions explicitly calculated in perturbative QCD. Phenomenological applications of these sum rules are discussed.