First CLAS12 Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries in the Extended Valence Region
G. Christiaens, M. Defurne, D. Sokhan, P. Achenbach, Zaenal Akbar, M. J. Amaryan, H. Ataç, H. Avakian, C. Ayerbe Gayoso, L. Baashen, N. A. Baltzell, L. Barion, M. Bashkanov, M. Battaglieri, I. Bedlinskiy, Bruno Benkel, F. Benmokhtar, A. Bianconi, A. S. Biselli, M. Bondi, W. A. Booth, F. Bossù, S. Boiarinov, K.-Th. Brinkmann, W. J. Briscoe, S. Bueltmann, D. Bulumulla, V. D. Burkert, T. Cao, D. S. Carman, J. C. Carvajal, A. Celentano, P. Chatagnon, V. Chesnokov, T. Chetry, G. Ciullo, G. Clash, P. L. Cole, M. Contalbrigo, G. Costantini, A. D’Angelo, N. Dashyan, R. De Vita, A. Deur, S. Diehl, C. Dilks, C. Djalali, R. Dupré, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, L. Elouadrhiri, S. Fegan, A. Filippi, K. Gates, G. Gavalian, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, D. I. Glazier, A. A. Golubenko, G. Gosta, R. W. Gothe, Y. Gotra, K. A. Griffioen, M. Guidal, K. Hafidi, H. Hakobyan, M. Hattawy, F. Hauenstein, T. B. Hayward, D. Heddle, A. Hobart, D. E. Holmberg, M. Holtrop, Y. Ilieva, D. G. Ireland, E. L. Isupov, H. S. Jo, D. Keller, M. Khachatryan, A. Khanal, W. Kim, A. Kripko, V. Kubarovsky, S. E. Kuhn, V. Lagerquist, L. Lanza, M. L. Kabir, M. Leali, S. Lee, P. Lenisa, X. Li, K. Livingston, I . J . D. MacGregor, D. Marchand, V. Mascagna, G. Matousek, B. McKinnon
Abstract
Deeply virtual Compton scattering (DVCS) allows one to probe generalized parton distributions describing the 3D structure of the nucleon. We report the first measurement of the DVCS beam-spin asymmetry using the CLAS12 spectrometer with a 10.2 and 10.6 GeV electron beam scattering from unpolarized protons. The results greatly extend the Q^{2} and Bjorken-x phase space beyond the existing data in the valence region and provide 1600 new data points measured with unprecedented statistical uncertainty, setting new, tight constraints for future phenomenological studies.