Sum rules (quantum field theory)

In quantum field theory, a sum rule is a relation between a static quantity and an integral over a dynamical quantity. Therefore, they have a form such as: where is the dynamical quantity, for example a structure function characterizing a particle, and is the static quantity, for example the mass or the charge of that particle. Quantum field theory sum rules should not be confused with sum rules in quantum chromodynamics or quantum mechanics. rdf:langString