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arXiv · 1012.3676

Ratios of Helicity Amplitudes for Exclusive rho-0 Electroproduction

The HERMES Collaboration·A. Airapetian·N. Akopov·Z. Akopov·E. C. Aschenauer·W. Augustyniak·R. Avakian·A. Avetissian·E. Avetisyan·S. Belostotski·N. Bianchi·H. P. Blok·A. Borissov·J. Bowles·V. Bryzgalov·J. Burns·M. Capiluppi·G. P. Capitani·E. Cisbani·G. Ciullo·M. Contalbrigo·P. F. Dalpiaz·W. Deconinck·R. De Leo·L. De Nardo·E. De Sanctis·M. Diefenthaler·P. Di Nezza·M. Dueren·M. Ehrenfried·G. Elbakian·F. Ellinghaus·R. Fabbri·A. Fantoni·L. Felawka·S. Frullani·D. Gabbert·G. Gapienko·V. Gapienko·F. Garibaldi·G. Gavrilov·V. Gharibyan·F. Giordano·S. Gliske·M. Golembiovskaya·C. Hadjidakis·M. Hartig·D. Hasch·G. Hill·A. Hillenbrand·M. Hoek·Y. Holler·I. Hristova·Y. Imazu·A. Ivanilov·H. E. Jackson·H. S. Jo·S. Joosten·R. Kaiser·G. Karyan·T. Keri·E. Kinney·A. Kisselev·N. Kobayashi·V. Korotkov·V. Kozlov·P. Kravchenko·V. G. Krivokhijine·L. Lagamba·R. Lamb·L. Lapikas·I. Lehmann·P. Lenisa·L. A. Linden-Levy·A. Lopez Ruiz·W. Lorenzon·X. -G. Lu·X. -R. Lu·B. -Q. Ma·D. Mahon·N. C. R. Makins·S. I. Manaenkov·L. Manfre·Y. Mao·B. Marianski·A. Martinez de la Ossa·H. Marukyan·C. A. Miller·Y. Miyachi·A. Movsisyan·V. Muccifora·M. Murray·A. Mussgiller·E. Nappi·Y. Naryshkin·A. Nass·M. Negodaev·W. -D. Nowak·L. L. Pappalardo·R. Perez-Benito
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Abstract

Exclusive rho^0-meson electroproduction is studied in the HERMES experiment, using a 27.6 GeV longitudinally polarized electron/positron beam and unpolarized hydrogen and deuterium targets in the kinematic region 0.5 GeV^2 < Q^2 < 7.0 GeV^2, 3.0 GeV < W < 6.3 GeV, and -t' < 0.4 GeV^2. Real and imaginary parts of the ratios of the natural-parity-exchange helicity amplitudes T_{11} (\gamma^*_T --> \rho_T), T_{01} (\gamma^*_T --> \rho_L), T_{10} (\gamma^*_L --> \rho_T), and T_{1-1} (\gamma^*_{-T} -->\rho_T) to T_{00} (\gamma^*_L --> \rho_L) are extracted from the data. For the unnatural-parity-exchange amplitude U_{11}, the ratio |U_{11}/T_{00}| is obtained. The Q^2 and t' dependences of these ratios are presented and compared with perturbative QCD predictions.

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The HERMES Collaboration, A. Airapetian, N. Akopov, Z. Akopov, E. C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetisyan, S. Belostotski, N. Bianchi, H. P. Blok, A. Borissov, J. Bowles, V. Bryzgalov, J. Burns, M. Capiluppi, G. P. Capitani, E. Cisbani, G. Ciullo, M. Contalbrigo, P. F. Dalpiaz, W. Deconinck, R. De Leo, L. De Nardo, E. De Sanctis, M. Diefenthaler, P. Di Nezza, M. Dueren, M. Ehrenfried, G. Elbakian, F. Ellinghaus, R. Fabbri, A. Fantoni, L. Felawka, S. Frullani, D. Gabbert, G. Gapienko, V. Gapienko, F. Garibaldi, G. Gavrilov, V. Gharibyan, F. Giordano, S. Gliske, M. Golembiovskaya, C. Hadjidakis, M. Hartig, D. Hasch, G. Hill, A. Hillenbrand, M. Hoek, Y. Holler, I. Hristova, Y. Imazu, A. Ivanilov, H. E. Jackson, H. S. Jo, S. Joosten, R. Kaiser, G. Karyan, T. Keri, E. Kinney, A. Kisselev, N. Kobayashi, V. Korotkov, V. Kozlov, P. Kravchenko, V. G. Krivokhijine, L. Lagamba, R. Lamb, L. Lapikas, I. Lehmann, P. Lenisa, L. A. Linden-Levy, A. Lopez Ruiz, W. Lorenzon, X. -G. Lu, X. -R. Lu, B. -Q. Ma, D. Mahon, N. C. R. Makins, S. I. Manaenkov, L. Manfre, Y. Mao, B. Marianski, A. Martinez de la Ossa, H. Marukyan, C. A. Miller, Y. Miyachi, A. Movsisyan, V. Muccifora, M. Murray, A. Mussgiller, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W. -D. Nowak, L. L. Pappalardo, R. Perez-Benito. 2010-12-16. Ratios of Helicity Amplitudes for Exclusive rho-0 Electroproduction. https://doi.org/10.1140/epjc/s10052-011-1609-2

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