Related Experiment Video
Updated: Jul 19, 2026

Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Measurement of deeply virtual compton scattering with a polarized-proton target
S Chen1, H Avakian, V D Burkert
1Florida State University, Tallahassee, Florida 32306, USA.
Researchers measured the longitudinal target-spin asymmetry for exclusive high-energy photon electroproduction. The study observed a significant azimuthal dependence, confirming theoretical predictions for generalized parton distributions.
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Chromodynamics
Background:
- Exclusive high-energy photon electroproduction (ep→eγp) provides a unique window into the nucleon's internal structure.
- Understanding generalized parton distributions (GPDs) is crucial for a complete picture of nucleon structure.
- Previous measurements lacked the precision to fully constrain GPDs related to spin phenomena.
Purpose of the Study:
- To measure the longitudinal target-spin asymmetry (AUL) for the first time in the exclusive electroproduction of high-energy photons.
- To investigate the azimuthal angular dependence of this asymmetry.
- To provide experimental data sensitive to specific generalized parton distributions (GPDs), namely H and H.
Main Methods:
- Data acquisition at Jefferson Lab (JLab) using the CEBAF Large Acceptance Spectrometer (CLAS).
- Experiment utilized 5.7 GeV electrons and a longitudinally polarized ammonia (NH3) target.
- Analysis focused on the exclusive reaction ep→eγp, measuring the target-spin asymmetry AUL.
Main Results:
- A significant azimuthal (sinφ) angular dependence was observed in the target-spin asymmetry.
- The amplitude of the sinφ moment was determined to be 0.252 ± 0.042 (stat) ± 0.020 (sys).
- The observed asymmetry and its kinematic dependence showed good agreement with theoretical calculations.
Conclusions:
- The measured longitudinal target-spin asymmetry provides crucial experimental constraints on generalized parton distributions.
- The observed azimuthal dependence is a direct consequence of the interference between deeply virtual Compton scattering and Bethe-Heitler processes.
- This study demonstrates the sensitivity of the AUL measurement to the GPDs H and H, advancing our understanding of nucleon spin structure.
More Related Videos
08:22Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
11:27Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2
Published on: December 8, 2016
Related Concept Videos
Potential Due to a Polarized Object
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
Electric Dipoles and Dipole Moment
Theoretically, studying electric dipoles leads to understanding why the resultant electric forces around us are weak. Since electric forces are strong, remnant net charges are rare. Hence, the interaction between dipoles helps us understand electrical interactions in...
Coulomb's Law
Newton's third law applies to the Coulomb force — the force on...
π Electron Effects on Chemical Shift: Overview
Atomic Nuclei: Nuclear Spin State Population Distribution