Deeply Virtual Compton Scattering at Hall A, Jefferson Lab

The Standard Model of particle physics defines quarks and leptons as the basic building blocks of all matter. The interaction between them are mediated by force carrying gauge bosons. Quantum ChromoDynamics (QCD), the theory that explains the strong interaction is still not complete enough to derive the physical observables of a Quark-Gluon system from the fundamental degrees of freedom of it’s constituents. Experimentally observable single particle densities provide important insights into our understanding of the quark-gluon system and hence help fill in the gaps of QCD. Generalized Parton Distributions (GPDs) provide simultaneous information of both spacial and longitudinal momentum distributions of constituents of a quark-gluon system. Deeply Virtual Compton Scattering (DVCS) is understood to be the simplest and cleanest process to access GPDs. Even though the exclusive DVCS is simple to understand, the experimental process however, is complex with the Bethe-Heitler and Associated DVCS being in the mix of the electron proton scattering. Over the years, 3 generations of DVCS experiments have been conducted in the Experimental Hall-A of Thomas Jefferson National Accelerator Facility (JLab). This thesis presents the extraction of DVCS cross section in 9 total kinematic points from the 3rd generation experiment (DVCS3) conducted after the 12 GeV upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) of JLab during Fall 2014 - Fall 2016

Deep Exclusive Electroproduction of \u3ci\u3eπ\u3c/i\u3e\u3csup\u3e0\u3c/sup\u3e at High \u3ci\u3eQ\u3c/i\u3e\u3csup\u3e2\u3c/sup\u3e in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of B (0.36, 0.48, and 0.60) and Q2 (3.1 to 8.4  GeV2) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσT/dt+εdσL/dt, dσTT/dt, dσLT/dt, and dσLT′/dt are extracted as a function of the proton momentum transfer t−tmin. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon