Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction
Abstract
The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized HERA positron beam scattering off an unpolarized hydrogen target is measured at HERMES. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe--Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of background from events, which was estimated to contribute an average of about 12% to the signal in previous HERMES publications. The removal of this background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0.054 +/- 0.016 to -0.328 +/- 0.027 (stat.) +/- 0.045 (syst.).
Keywords
Cite
@article{arxiv.1206.5683,
title = {Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction},
author = {The HERMES Collaboration and A. Airapetian and N. Akopov and Z. Akopov and E. C. Aschenauer and W. Augustyniak and R. Avakian and A. Avetissian and E. Avetisyan and S. Belostotski and H. P. Blok and A. Borissov and J. Bowles and I. Brodski and V. Bryzgalov and J. Burns and M. Capiluppi and G. P. Capitani and E. Cisbani and G. Ciullo and M. Contalbrigo and P. F. Dalpiaz and W. Deconinck and R. De Leo and L. De Nardo and E. De Sanctis and M. Diefenthaler and P. Di Nezza and M. Düren and M. Ehrenfried and G. Elbakian and F. Ellinghaus and E. Etzelmüller and R. Fabbri and A. Fantoni and L. Felawka and S. Frullani and G. Gapienko and V. Gapienko and F. Garibaldi and G. Gavrilov and V. Gharibyan and F. Giordano and S. Gliske and M. Golembiovskaya and I. M. Gregor and H. Guler and M. Hartig and D. Hasch and A. Hillenbrand and M. Hoek and Y. Holler and I. Hristova and A. Ivanilov and H. E. Jackson and H. S. Jo and S. Joosten and R. Kaiser and G. Karyan and T. Keri and E. Kinney and A. Kisselev and V. Korotkov and V. Kozlov and B. Krauss and P. Kravchenko and V. G. Krivokhijine and L. Lagamba and L. Lapikás and I. Lehmann and P. Lenisa and A. López Ruiz and W. Lorenzon and S. Lu and X. Lu and B. -Q. Ma and D. Mahon and N. C. R. Makins and S. I. Manaenkov and L. Manfré and Y. Mao and B. Marianski and A. Martinez de la Ossa and H. Marukyan and C. A. Miller and Y. Miyachi and A. Movsisyan and M. Murray and A. Mussgiller and E. Nappi and Y. Naryshkin and A. Nass and M. Negodaev and W. -D. Nowak and A. Osborne and L. L. Pappalardo and R. Perez-Benito and A. Petrosyan and P. E. Reimer and A. R. Reolon and C. Riedl and K. Rith and G. Rosner and A. Rostomyan and L. Rubacek and J. Rubin and D. Ryckbosch and A. Schäfer and G. Schnell and K. P. Schüler and B. Seitz and C. Shearer and T. -A. Shibata and V. Shutov and M. Stancari and M. Statera and J. J. M. Steijger and J. Stewart and S. Taroian and A. Terkulov and R. Truty and A. Trzcinski and M. Tytgat and Y. Van Haarlem and C. Van Hulse and D. Veretennikov and V. Vikhrov and I. Vilardi and S. Wang and S. Yaschenko and Z. Ye and S. Yen and V. Zagrebelnyy and D. Zeiler and B. Zihlmann and P. Zupranski},
journal= {arXiv preprint arXiv:1206.5683},
year = {2012}
}