Beam Charge Asymmetries for Deeply Virtual Compton Scattering on the Proton at CLAS12
Sep 25, 2023Citations per year
Abstract: (arXiv)
The parameterization of the nucleon structure through Generalized Parton Distributions (GPDs) shed a new light on the nucleon internal dynamics. For its direct interpretation, Deeply Virtual Compton Scattering (DVCS) is the golden channel for GPDs investigation. The DVCS process interferes with the Bethe-Heitler (BH) mechanism to constitute the leading order amplitude of the process. The study of the reaction with polarized positron and electron beams gives a complete set of unique observables to unravel the different contributions to the cross section. This separates the different reaction amplitudes, providing a direct access to their real and imaginary parts which procures crucial constraints on the model dependences and associated systematic uncertainties on GPDs extraction. The real part of the BH-DVCS interference amplitude is particularly sensitive to the -term which parameterizes the Gravitational Form Factors of the nucleon. The separation of the imaginary parts of the interference and DVCS amplitudes provides insights on possible higher-twist effects. We propose to measure the unpolarized and polarized Beam Charge Asymmetries (BCAs) of the process on an unpolarized hydrogen target with {\tt CLAS12}, using polarized positron and electron beams at 10.6 GeV. The azimuthal and -dependences of the unpolarized and polarized BCAs will be measured over a large phase space using a 100 day run with a luminosity of 0.66cms.Note:
- Proposal to the Jefferson Lab Program Advisory Committee (PAC51)
- electron: beam
- charge: asymmetry
- hydrogen: target
- parton: distribution function
- higher-order: 0
- nucleon: form factor
- effect: higher-twist
- nucleon: structure
- deeply virtual Compton scattering
- generalized parton distribution
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