GUMP program for GPD global analysis: quark GPDs from DVCS

We present the first global analysis of generalized parton distributions (GPDs) combing lattice Quantum Chromodynamics (QCD) calculations and experiment measurements including global Parton Distribution Functions (PDFs), Form Factors (FFs) and Deeply Virtual Compton Scattering (DVCS) measurements. Following the previous work where we parameterize GPDs in terms of their moments, we extend the framework to allow for the global analysis at non-zero skewness. Together with the constraints at zero skewness, we fit GPDs to global DVCS measurements from both the recent JLab and the earlier Hadron-Electron Ring Accelerator (HERA) experiments with two active quark flavors and leading order QCD evolution. With certain choices of empirical constraints, both sea and valence quark distributions are extracted with the combined inputs, and we present the quark distributions in proton correspondingly. We also discuss how to extend the framework to accommodate more off-forward constrained beyond the small $xi$ expansion, especially the lattice calculated GPDs.