Spin Dependence of Diffractive Vector Meson Production

TL;DR

This paper reviews recent theoretical advances in understanding spin effects in diffractive vector meson production, highlighting how SCHNC phenomena reveal quark spin-orbit interactions and challenging existing sum rules in QCD.

Contribution

It provides a comprehensive review of SCHNC effects in diffractive DIS and discusses experimental prospects at JLab to probe these phenomena in QCD pomeron exchange.

Findings

SCHNC effects serve as a probe of spin-orbit coupling in vector mesons

JLab experiments can test SCHNC in QCD pomeron exchange

Unitarity effects challenge the Burkhardt-Cottingham sum rule

Abstract

I review the recent progress in the theory of s-channel helicity nonconservation (SCHNC) effects in diffractive DIS. SCHNC in diffractive vector meson production is an unique probe of the spin-orbit coupling and Fermi motion of quarks in vector mesons. Photo- and electroproduction of the $\phi$ and its radial and angular excitations at Jlab is perfectly posed to probe SCHNC in QCD pomeron exchange. I also discuss the unitarity driven demise of the Burkhardt-Cottingham sum rule and large & scaling departure from the Wandzura-Wilczek relation.