Measurement of angular distributions and R = σLT in diffractive electroproduction of ρ0 mesons

K. Ackerstaff, A. Airapetian, N. Akopov, M. Amarian, E. C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, B. Bains, M. Beckmann, S. Belostotski, J. E. Belz, Th Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. BrackB. Braun, B. Bray, W. Brückner, A. Brüll, E. E.W. Bruins, H. J. Bulten, G. P. Capitani, P. Carter, E. Cisbani, G. R. Court, P. P.J. Delheij, E. De Sanctis, D. De Schepper, E. Devitsin, P. K.A. de Witt Huberts, M. Düren, A. Dvoredsky, G. Elbakian, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, K. Fiedler, B. W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, M. A. Funk, Y. Gärber, N. D. Gagunashvili, P. Galumian, H. Gao, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Grosshauser, A. Gute, V. Gyurjyan, J. P. Haas, W. Haeberli, O. Häusser, J. O. Hansen, D. Hasch, R. Henderson, Th Henkes, R. Hertenberger, Y. Holler, R. J. Holt, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, K. Königsmann, M. Kolstein, H. Kolster, W. Korsch, V. Kozlov, L. H. Kramer, B. Krause, V. G. Krivokhijine, M. Kückes, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N. C.R. Makins, S. I. Manaenkov, F. K. Martens, J. W. Martin, A. Mateos, K. Mcllhany, R. D. McKeown, F. Meissner, F. Menden, D. Mercer, A. Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, R. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A. M. Nathan, F. Neunreither, J. M. Niczyporuk, W. D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T. G. O'Neill, R. Openshaw, J. Ouyang, S. F. Pate, M. Pitt, H. R. Poolman, S. Potashov, D. H. Potterveld, G. Rakness, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, G. Röper, H. O. Roloff, P. Rossi, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, K. P. Schüler, A. Schwind, T. A. Shibata, T. Shin, A. Simon, K. Sinram, W. R. Smythe, J. Sowinski, M. Spengos, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stösslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D. M. Thiessen, B. Tipton, A. Trudel, M. Tytgat, G. M. Urciuoli, J. F.J. van den Brand, G. van der Steenhoven, R. van de Vyver, M. C. Vetterli, M. G. Vincter, E. Volk, W. Wander, T. P. Welch, S. E. Williamson, T. Wise, K. Zapfe, H. Zohrabian

研究成果: Article査読

21 被引用数 (Scopus)

抄録

Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the ρ0(770) meson over a range in the virtual photon negative four-momentum squared 0.5 < Q2 < 4 GeV2 and the photon-nucleon invariant mass range 3.8 < W < 6.5 GeV. The experiment was performed with the HERMES spectrometer, using a longitudinally polarized positron beam and a 3He gas target internal to the HERA e± storage ring. The event sample combines ρ0 mesons produced incoherently off individual nucleons and coherently off the nucleus as a whole. The distributions in one production angle and two angles describing the ρ0 → π+π- decay yielded measurements of eight elements of the spin-density matrix, including one that had not been measured before. The results are consistent with the dominance of helicity conserving amplitudes and natural parity exchange. The improved precision achieved at 4 < W < 7 GeV, in combination with other data at W > 7 GeV, reveals evidence for an energy dependence in the ratio R of the longitudinal to transverse cross sections at constant Q2.

本文言語English
ページ(範囲)303-316
ページ数14
ジャーナルEuropean Physical Journal C
18
2
DOI
出版ステータスPublished - 2000
外部発表はい

ASJC Scopus subject areas

  • 工学(その他)
  • 物理学および天文学(その他)

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