A narrow-resonance model for a two-current two-particle amplitude with gauge invariance and scaling

Abstract

The four-point function of two off-shell currents and two on-shell scalar fields is analysed. The only singularities considered are simple poles lying on linear trajectories. The behaviour for high-current masses and high energies corresponds to a scaling appropriate for a canonical light-cone singularity. The four-point function satisfies the Ward identity for one of the currents and is thus gauge invariant. General functions satisfying these requirements are constructed. It is shown that gauge invariance in no way conflicts with the strong light-cone dominance (duality) and consequently Drell-Yan-West-type relations can be easily incorporated.