Extraction of generalized parton distribution observables from deeply virtual electron proton scattering experiments
We provide the general expression of the cross section for exclusive deeply virtual photon electroproduction from a spin-1/2 target using current parametrizations of the off-forward correlation function in a nucleon for different beam and target polarization configurations up to twist-three accuracy. All contributions to the cross section including deeply virtual Compton scattering, the Bethe-Heitler process, and their interference, are described within a helicity-amplitude-based framework which is also relativistically covariant and readily applicable to both the laboratory frame and in a collider kinematic setting. Our formalism renders a clear physical interpretation of the various components of the cross section by making a connection with the known characteristic structure of the electron scattering coincidence reactions. In particular, we focus on the total angular momentum, $$J_z$$, and on the orbital angular momentum, $$L_z$$. On one side, we uncover an avenue to a precise extraction of $$J_z$$, given by the combination of generalized parton distributions, $$\textit{H}$$ + $$\textit{E}$$, through a generalization of the Rosenbluth separation method used in elastic electron proton scattering. On the other side, we single out for the first time, the twist-three angular modulations of the cross section that are sensitive to $$L_z$$. The proposed generalized Rosenbluth technique adds constraints and can be extended to additional observables relevant to the mapping of the three-dimensional structure of the nucleon.
- Research Organization:
- Univ. of Virginia, Charlottesville, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0016286; FG02-96ER40950
- OSTI ID:
- 1604844
- Alternate ID(s):
- OSTI ID: 1800850
- Journal Information:
- Physical Review D, Journal Name: Physical Review D Vol. 101 Journal Issue: 5; ISSN 2470-0010
- Publisher:
- American Physical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Deeply Virtual Exclusive Reactions with CLAS
Theory of deeply virtual Compton scattering off the unpolarized proton