Deeply Virtual Compton Scattering and Meson Production at JLab/CLAS

TL;DR

This paper reviews recent CLAS collaboration results on DVCS and DVMP, discussing their interpretation within GPD frameworks and highlighting successes and limitations of current models in explaining experimental data.

Contribution

It provides a comprehensive analysis of recent experimental data on DVCS and DVMP at JLab, evaluating the applicability of GPD models and discussing future experimental prospects with CLAS12.

Findings

DVCS data are compatible with GPD models.

GPD models currently fail to describe most DVMP data.

GPD mechanism applies to $\,phi$ meson production.

Abstract

This report reviews the recent experimental results from the CLAS collaboration (Hall B of Jefferson Lab, or JLab) on Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) and discusses their interpretation in the framework of Generalized Parton Distributions (GPDs). The impact of the experimental data on the applicability of the GPD mechanism to these exclusive reactions is discussed. Initial results obtained from JLab 6 GeV data indicate that DVCS might already be interpretable in this framework while GPD models fail to describe the exclusive meson production (DVMP) data with the GPD parameterizations presently used. An exception is the $\phi$ meson production for which the GPD mechanism appears to apply. The recent global analyses aiming to extract GPDs from fitting DVCS CLAS and world data are discussed. The GPD experimental program at CLAS12, planned with the upcoming 12 GeV upgrade of JLab, is briefly presented.