Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

S. Pisano, A. Biselli, S. Niccolai, E. Seder, M. Guidal, M. Mirazita, K. P. Adhikari, D. Adikaram, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, H. Avakian, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, P. Bosted, B. Briscoe, J. Brock, W. K. BrooksV. D. Burkert, C. Carlin, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, N. Compton, M. Contalbrigo, O. Cortes, D. G. Crabb, V. Crede, A. D'Angelo, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, Gary Smith, D. P. Watts, Nicholas Zachariou, L. Zana, CLAS Collaboration

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Single-beam, single-target, and double spin asymmetries for hard exclusive electroproduction of a photon on the proton (e) over right arrow(p) over right arrow. e'p'gamma are presented. The data were taken at Jefferson Lab using the CEBAF large acceptance spectrometer and a longitudinally polarized (NH3)-N-14 target. The three asymmetries were measured in 165 four-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of generalized parton distributions. The measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the H and (H) over tilde Compton form factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.

Original languageEnglish
Article number052014
Number of pages27
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number5
Publication statusPublished - 19 Mar 2015


  • QCD

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