Measurement of azimuthal asymmetries with respect to both beam charge and transverse target polarization in exclusive electroproduction of real photons

HERMES collaboration; A. Airapetian; N. Akopov; Z. Akopov; A. Andrus; E. C. Aschenauer; W. Augustyniak; R. Avakian; A. Avetissian; E. Avetisyan; BARION, Luca; S. Belostotski; N. Bianchi; H. P. Blok; H. Böttcher; C. Bonomo; A. Borissov; A. Brüll; V. Bryzgalov; J. Burns; CAPILUPPI, Marco; G. P. Capitani; E. Cisbani; CIULLO, Giuseppe; CONTALBRIGO, Marco; FERRETTI, Paola; W. Deconinck; R. De Leo; M. Demey; L. De Nardo; E. De Sanctis; M. Diefenthaler; P. Di Nezza; J. Dreschler; M. Düren; M. Ehrenfried; G. Elbakian; F. Ellinghaus; U. Elschenbroich; R. Fabbri; A. Fantoni; L. Felawka; S. Frullani; A. Funel; D. Gabbert; G. Gapienko; V. Gapienko; F. Garibaldi; G. Gavrilov; V. Gharibyan; GIORDANO, Francesca; S. Gliske; H. Guler; C. Hadjidakis; D. Hasch; T. Hasegawa; G. Hill; A. Hillenbrand; M. Hoek; Y. Holler; I. Hristova; G. Iarygin; Y. Imazu; A. Ivanilov; A. Izotov; H. E. Jackson; A. Jgoun; S. Joosten; R. Kaiser; T. Keri; E. Kinney; A. Kisselev; M. Kopytin; V. Korotkov; V. Kozlov; P. Kravchenko; V. G. Krivokhijine; L. Lagamba; R. Lamb; L. Lapikás; I. Lehmann; LENISA, Paolo; L. A. Linden Levy; W. Lorenzon; S. Lu; X. Lu; B. Q. Ma; D. Mahon; B. Maiheu; N. C. R. Makins; Y. Mao; B. Marianski; H. Marukyan; C. A. Miller; Y. Miyachi; V. Muccifora; M. Murray; A. Mussgiller; A. Nagaitsev; E. Nappi; Y. Naryshkin; A. Nass; M. Negodaev; W. D. Nowak; A. Osborne; PAPPALARDO, Luciano Libero; R. Perez Benito; N. Pickert; M. Raithel; P. E. Reimer; A. Reischl; A. R. Reolon; C. Riedl; K. Rith; S. E. Rock; G. Rosner; A. Rostomyan; L. Rubacek; J. Rubin; A. L. Ruiz; D. Ryckbosch; Y. Salomatin; I. Sanjiev; A. Schäfer; G. Schnell; K. P. Schüler; B. Seitz; C. Shearer; T. A. Shibata; V. Shutov; STANCARI, Michelle Dawn; STATERA, Marco; E. Steffens; J. J. M. Steijger; H. Stenzel; J. Stewart; F. Stinzing; P. Tait; S. Taroian; A. Terkulov; A. Trzcinski; M. Tytgat; A. Vandenbroucke; P. B. van der Nat; G. van der Steenhoven; Y. Van Haarlem; C. Van Hulse; M. Varanda; D. Veretennikov; V. Vikhrov; I. Vilardi; C. Vogel; S. Wang; S. Yaschenko; H. Ye; Z. Ye; S. Yen; W. Yu; D. Zeiler; B. Zihlmann; P. Zupranski

doi:10.1088/1126-6708/2008/06/066

Azimuthal asymmetries in exclusive electroproduction of real photons are measured for the first time with respect to transverse target polarisation, providing new constraints on Generalized Parton Distributions. From the same data set on a hydrogen target, new results for the beam-charge asymmetry are also extracted with better precision than those previously reported. By comparing model calculations with measured asymmetries attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes, a model-dependent constraint is obtained on the total angular momenta carried by up and down quarks in the nucleon.