학술논문
Beam Charge Asymmetries for Deeply Virtual Compton Scattering on the Proton at CLAS12
Document Type
Working Paper
Author
Voutier, E.; Burkert, V.; Niccolai, S.; Paremuzyan, R.; Afanasev, A.; Alvarado-Galeano, J. -S.; Atoui, M.; Barion, L.; Battaglieri, M.; Bernauer, J.; Bianconi, A.; Bondi, M.; Briscoe, W.; Camsonne, A.; Capobianco, R.; Celentano, A.; Chatagnon, P.; Chetry, T.; Ciullo, G.; Cole, P.; Contalbrigo, M.; Costantini, G.; Defurne, M.; Deur, A.; De Vita, R.; Diehl, S.; Dupré, R.; Elouadrhiri, L.; Fernando, I.; Filippi, A.; Forest, T.; Girod, F. -X.; Gosta, G.; Grames, J.; Gueye, P.; Habet, S.; Hattawy, M.; Higinbotham, D.; Hobart, A.; Hyde, C.; Joo, K.; Kim, A.; Klimenko, V.; Kubarovsky, V.; Leali, M.; Lenisa, P.; Marchand, D.; Marsicano, L.; Mascagna, V.; Matamoros, D.; McCaughan, M.; McKinnon, B.; Migliorati, S.; Mitra, H. S.; Movsisyan, A.; Muñoz-Camacho, C.; Osipenko, M.; Ouillon, M.; Pappalardo, L.; Pasquini, B.; Pasyuk, E.; Pilleux, N.; Poelker, M.; Raue, B.; Ripani, M.; Santos, R.; Schmidt, A.; Singh, R.; Sokhan, D.; Spreafico, M.; Stoler, P.; Strakovsky, I.; Taiuti, M.; Venturelli, L.; Wang, P. -K.; Wei, X.; Zhao, Z.; Collaboration, the CLAS; Group, the Jefferson Lab Positron Working
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Abstract
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 $eN \to eN\gamma$ process. The study of the $ep\gamma$ reaction with polarized positron and electron beams gives a complete set of unique observables to unravel the different contributions to the $ep \gamma$ 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 $D$-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 $\vec{e}^{\pm}p \to e^{\pm}p \gamma$ process on an unpolarized hydrogen target with {\tt CLAS12}, using polarized positron and electron beams at 10.6 GeV. The azimuthal and $t$-dependences of the unpolarized and polarized BCAs will be measured over a large $(x_B,Q^2)$ phase space using a 100 day run with a luminosity of 0.66$\times 10^{35}$cm$^{-2}\cdot$s$^{-1}$.
Comment: Proposal to the Jefferson Lab Program Advisory Committee (PAC51)
Comment: Proposal to the Jefferson Lab Program Advisory Committee (PAC51)