DIS2021 Workshop Proceedings: Backward-Angle (u-Channel) Meson Production from JLab 12 GeV Hall C to EIC

TL;DR

This paper discusses recent findings and theoretical insights into backward-angle meson production in electron-proton scattering, highlighting its potential to expand understanding of QCD and nucleon structure at JLab and future colliders.

Contribution

It provides a comprehensive summary of experimental results, theoretical developments, and future research directions in u-channel meson electroproduction at high-energy electron scattering facilities.

Findings

Evidence of QCD factorization applicability in u-channel kinematics

Unique interaction dynamics with target proton recoiling forward

Progress towards understanding nucleon structure via u-channel observables

Abstract

The recent exclusive backward-angle electroproduction of omega from Jefferson Lab Hall C electron-proton fixed-target scattering experiments above the resonance region hints at a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. Thanks to this effort, the interest in studying nucleon structure through u-channel meson production observables has grown significantly. In the fixed target configuration, the u-channel meson electroproduction observables feature a unique interaction picture: the target proton absorbs nearly all momentum induced by virtual photons and recoils forward, while the produced mesons (such as omega or pions) are left behind almost at rest near the target station. In this presentation, We provide a summary of the key observations of the existing u-channel meson production results, update-to-date theory insights, and a path to further exploration from JLab 12 GeV Hall C program to the future Electron-Ion Colliders.