Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering

Abstract

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this work, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering (DVCS) off a proton bound in ${}^4$He. The data used here were accumulated using a $6$ GeV longitudinally polarized electron beam incident on a pressurized ${}^4$He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle ($\varphi$) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The $Q^2$, $x_B$, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20\% to 40\%, indicating possible medium modification of its partonic structure.

References in corpus (7)

• Nucleon Electromagnetic Form Factors
• Nucleon-Nucleon Correlations, Short-lived Excitations, and the Quarks Within
• Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target
• Longitudinal target-spin asymmetries for deeply virtual Compton scattering
• Tomographic image of the proton
• The dual parameterization of the proton generalized parton distribution functions H and E and description of the DVCS cross sections and asymmetries
• First Exclusive Measurement of Deeply Virtual Compton Scattering off ${}^4$He: Toward the 3D Tomography of Nuclei

Cited by in corpus (13)

• The Present and Future of QCD
• 2D energy-momentum tensor distributions of nucleon in a large-$N_c$ quark model from ultra-relativistic to non-relativistic limit
• Twist-three cross-sections in deeply virtual Compton scattering
• Prospects for quarkonium studies at the high-luminosity LHC
• Twist-3 Generalized Parton Distribution for the Proton from Basis Light-Front Quantization
• Measurement of deeply virtual Compton scattering off Helium-4 with CLAS at Jefferson Lab
• Catching a glimpse of the parton structure of the bound proton
• Generalized parton distributions of $\Delta$ resonance in a diquark spectator approach
• Incoherent deeply virtual Compton scattering off ${}^4$He
• Deeply virtual Compton scattering off Helium nuclei with positron beams
• Generalized parton distributions of light nuclei
• Deciphering Twist-3 Chiral-Even GPDs in the Light-Front Quark-Diquark Model
• Deeply virtual Compton Scattering off ${}^4$He