; Ciullo, G. ; Contalbrigo, M. ; Dalpiaz, P. F. ; Deconinck, W.
; De Leo, R. ; Demey, M. ; De Nardo, L. ; De Sanctis, E. ; Diefenthaler, M. ; Di Nezza, P. ; Dreschler, J. ; Düren, M. ; Ehrenfried, M. ; Elalaoui-Moulay, A. ; Elbakian, G. ; Ellinghaus, F.
; Elschenbroich, U. ; Fabbri, R. ; Fantoni, A. ; Felawka, L. ; Frullani, S. ; Funel, A. ; Gabbert, D. ; Gapienko, G. ; Gapienko, V. ; Garibaldi, F. ; Gavrilov, G. ; Gharibyan, V. ; Giordano, F. ; Gliske, S.
; Grebeniouk, O. ; Gregor, I. M. ; Guler, H. ; Hadjidakis, C. ; Hartig, M. ; Hasch, D. ; Hasegawa, T. ; Hesselink, W. H. A. ; Hill, G. ; Hillenbrand, A. ; Hoek, M.
; Holler, Y. ; Hommez, B. ; Hristova, I. ; Iarygin, G. ; Imazu, Y. ; Ivanilov, A. ; Izotov, A. ; Jackson, H. E. ; Jgoun, A. ; Kaiser, R. ; Keri, T. ; Kinney, E. ; Kisselev, A. ; Kobayashi, T. ; Kopytin, M. ; Korotkov, V. ; Kozlov, V. ; Kravchenko, P. ; Krivokhijine, V. G. ; Lagamba, L.
; Lamb, R. ; Lapikás, L. ; Lehmann, I. ; Lenisa, P. ; Liebing, P. ; Linden-Levy, L. A. ; Lorenzon, W. ; Lu, S. ; Lu, X.-R. ; Ma, B.-Q. ; Maiheu, B. ; Makins, N. C. R. ; Manaenkov, S. I. ; Mao, Y. ; Marianski, B. ; Marukyan, H. ; Mexner, V. ; Miller, C. A. ; Miyachi, Y. ; Muccifora, V. ; Murray, M. ; Mussgiller, A. ; Nagaitsev, A. ; Nappi, E. ; Naryshkin, Y. ; Nass, A. ; Negodaev, M. ; Nowak, W.-D. ; Osborne, A. ; Pappalardo, L. L. ; Perez-Benito, R. ; Pickert, N. ; Raithel, M. ; Reggiani, D. ; Reimer, P. E.
; Reischl, A. ; Reolon, A. R. ; Riedl, C. ; Rith, K. ; Rock, S. E. ; Rosner, G. ; Rostomyan, A. ; Rubacek, L. ; Rubin, J. ; Ryckbosch, D. ; Salomatin, Y. ; Sanjiev, I. ; Schäfer, A. ; Schnell, G. ; Schüler, K. P. ; Seitz, B. ; Shearer, C. ; Shibata, T.-A. ; Shutov, V. ; Stancari, M. ; Statera, M. ; Steffens, J. E. ; Steijger, J. J. M. ; Stenzel, H. ; Stewart, J. ; Stinzing, F. ; Streit, J. ; Tait, P. ; Taroian, S. ; Tchuiko, B. ; Terkulov, A.
; Trzcinski, A. ; Tytgat, M.
; Vandenbroucke, A. ; van der Nat, P. B. ; van der Steenhoven, G. ; Van Haarlem, Y. ; Van Hulse, C. ; Varanda, M. ; Veretennikov, D. ; Vikhrov, V. ; Vilardi, I. ; Vogel, C. ; Wang, S. ; Yaschenko, S. ; Ye, H. ; Ye, Y. ; Ye, Z. ; Yen, S. ; Yu, W. ; Zeiler, D. ; Zihlmann, B. ; Zupranski, P. | Item type: | Article | ||||
|---|---|---|---|---|---|
| Journal or Publication Title: | The European Physical Journal C | ||||
| Publisher: | SPRINGER | ||||
| Place of Publication: | NEW YORK | ||||
| Volume: | 62 | ||||
| Number of Issue or Book Chapter: | 4 | ||||
| Page Range: | pp. 659-695 | ||||
| Date: | 2009 | ||||
| Institutions: | Physics > Institute of Theroretical Physics > Chair Professor Schäfer > Group Andreas Schäfer | ||||
| Identification Number: |
| ||||
| Keywords: | VECTOR-MESON PRODUCTION; INELASTIC-SCATTERING; CROSS-SECTION; P(0) MESONS; HERA; QCD; LEPTOPRODUCTION; DISTRIBUTIONS; POLARIMETER; HYDROGEN; | ||||
| Dewey Decimal Classification: | 500 Science > 530 Physics | ||||
| Status: | Published | ||||
| Refereed: | Yes, this version has been refereed | ||||
| Created at the University of Regensburg: | Yes | ||||
| Item ID: | 67005 |
Abstract
Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive rho (0) electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1 < Q (2)< 7 GeV2, 3.0 < W < ...

Abstract
Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive rho (0) electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1 < Q (2)< 7 GeV2, 3.0 < W < 6.3 GeV, and -t < 0.4 GeV2. Within the given experimental uncertainties, a hierarchy of relative sizes of helicity amplitudes is observed. Kinematic dependences of all SDMEs on Q (2) and t are presented, as well as the longitudinal-to-transverse rho (0) electroproduction cross-section ratio as a function of Q (2). A small but statistically significant deviation from the hypothesis of s-channel helicity conservation is observed. An indication is seen of a contribution of unnatural-parity-exchange amplitudes; these amplitudes are naturally generated with a quark-exchange mechanism.
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