Equal-Time Commutator and Superconvergence Sum Rule

Publisher Website
Google Scholar
Abstract
Applying the infinite-momentum technique to the matrix elements of equal-time commutators, we obtain superconvergence sum rules for the zero-mass-pion-nucleon scattering amplitude, which are identical with those derived from dispersion relations, apart from a possible restriction imposed upon trajectories with integer intercepts. Using this result, we show that a modification of the equal-time commutation relation of pion fields (or of divergence of the axial-vector currents) motivated by a simple quark model is not compatible with the Pomeranchuk theorem.