Diquark Substructure in $\phi$ Photoproduction

TL;DR

This paper explains forward and backward enhancements in $$ meson photoproduction via nonresonant diquark and triquark pairs, emphasizing quark collinearity constraints that favor configurations along the reaction axis.

Contribution

It introduces a diquark-triquark model to explain photoproduction enhancements, highlighting the role of quark collinearity in reaction dynamics.

Findings

Enhancements explained by diquark and triquark production.

Collinearity constraints favor configurations along the reaction axis.

Maximum amplitudes occur at minimal momentum transfer.

Abstract

Observed enhancements in the forward and backward directions for $\phi$ meson photoproduction off nucleons are shown to be explainable by the production of a nonresonant recoiling $(su)$ diquark, $(\bar s ud)$ triquark pair. We show that the necessity of maintaining approximate collinearity of the quarks within these units constrains configurations with the minimum momentum transfer, and hence maximal amplitudes, to lie preferentially along the reaction axis.