Exclusive Leptoproduction of Real Photons on a Longitudinally Polarised Hydrogen Target

Polarisation asymmetries are measured for the hard exclusive leptoproduction of real photons from a longitudinally polarised hydrogen target. These asymmetries arise from the deeply virtual Compton scattering and Bethe-Heitler processes. From the data are extracted two asymmetries in the azimuthal d...

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Veröffentlicht in:	arXiv.org 2010-04
Hauptverfasser:	The HERMES Collaboration, Akopov, N, Akopov, Z, Aschenauer, E C, Avakian, R, Avetissian, A, Avetisyan, E, Belostotski, S, Bianchi, N, Blok, H P, Bowles, J, Brodski, I, Bryzgalov, V, Burns, J, Capiluppi, M, Capitani, G P, Cisbani, E, Ciullo, G, Contalbrigo, M, Dalpiaz, P F, Deconinck, W, De Leo, R, De Sanctis, E, Dueren, M, Ehrenfried, M, Fantoni, A, Felawka, L, Frullani, S, Gabbert, D, Gapienko, G, Gapienko, V, Gharibyan, V, Giordano, F, Gliske, S, Golembiovskaya, M, Hartig, M, Hill, G, Holler, Y, Ivanilov, A, Izotov, A, Joosten, S, Kaiser, R, Keri, T, Kisselev, A, Kobayashi, N, Kozlov, V, Krivokhijne, V G, Lagamba, L, Lamb, R, Lapikas, L, Linden-Levy, L A, A Lopez~Ruiz, Lorenzon, W, X -G Lu, X -R Lu, Makins, N C R, Manaenkov, S I, Mao, Y, Marianski, B, A Martinez de la Ossa, Miller, C A, Miyachi, Y, Movsisyan, A, Murray, M, Nappi, E, Nass, A, Negodaev, M, Perez-Benito, R, Raithel, M, Reolon, A R, Riedl, C, Rosner, G, Rostomyan, A, Rubin, J, Ryckbosch, D, Salomatin, Y, Sanftl, F, Schnell, G, Schueler, K P, Seitz, B, T -A Shibata, Shutov, V, Statera, M, Steijger, J J M, Stinzing, F, Taroian, S, Trzcinski, A, Tytgat, M, P B van der Nat, Y Van Haarlem, C Van Hulse, Veretennikov, D, Vikhrov, V, Vilardi, I, Wang, S, H Ye, Z Ye, Yen, S, W Yu, Zihlmann, B
Format:	Artikel
Sprache:	eng
Schlagworte:	Elastic scattering Mathematical models Modulation Photons Physics - High Energy Physics - Experiment Polarization
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Beschreibung
Zusammenfassung:	Polarisation asymmetries are measured for the hard exclusive leptoproduction of real photons from a longitudinally polarised hydrogen target. These asymmetries arise from the deeply virtual Compton scattering and Bethe-Heitler processes. From the data are extracted two asymmetries in the azimuthal distribution of produced real photons about the direction of the exchanged virtual photon: A_UL with respect to the target polarisation and A_LL with respect to the product of the beam and target polarisations. Results for both asymmetries are compared to the predictions from a generalised parton distribution model. The sin(phi) and cos(0phi) amplitudes observed respectively for the A_UL and A_LL asymmetries are compatible with the sizeable predictions from the model. Unexpectedly, a sin(2phi) modulation in the A_UL asymmetry with a magnitude similar to that of the sin(phi) modulation is observed.
ISSN:	2331-8422
DOI:	10.48550/arxiv.1004.0177