Longitudinal Target-Spin Asymmetries for Deeply Virtual Compton Scattering

CLAS Collaboration, E. Seder, A. Biselli, S. Pisano, S. Niccolai*, Gary Smith, K. Joo, K. Adhikari, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, H. Avakian, M. Battaglieri, I. Bedlinskiy, J. Bono, S. Boiarinov, P. Bosted, W. Briscoe, J. Brock, W. K. BrooksS. Bueltmann, V. D. Burkert, D. S. Carman, C. Carlin, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, D. Crabb, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, D. Doughty, R. Dupre, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, A. Fradi, D. P. Watts, Nicholas Zachariou, L. Zana

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep. e'p'gamma. events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q(2), x(B), t, and phi, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Original languageEnglish
Article number032001
Number of pages7
JournalPhysical Review Letters
Issue number3
Publication statusPublished - 22 Jan 2015


  • CLAS


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