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

Journal Article

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.

Duke Authors

Cited Authors

  • Ackerstaff, K; Airapetian, A; Akopov, N; Amarian, M; Aschenauer, EC; Avakian, H; Avakian, R; Avetissian, A; Bains, B; Beckmann, M; Belostotski, S; Belz, JE; Benisch, T; Bernreuther, S; Bianchi, N; Blanchard, S; Blouw, J; Böttcher, H; Borissov, A; Brack, J; Braun, B; Bray, B; Brückner, W; Brüll, A; Bruins, EEW; Bulten, HJ; Capitani, GP; Carter, P; Cisbani, E; Court, GR; Delheij, PPJ; Sanctis, ED; Schepper, DD; Devitsin, E; Huberts, PKADW; Düren, M; Dvoredsky, A; Elbakian, G; Emerson, J; Fantoni, A; Fechtchenko, A; Ferstl, M; Fiedler, K; Filippone, BW; Fischer, H; Fox, B; Franz, J; Frullani, S; Funk, M-A; Gärber, Y; Gagunashvili, ND; Galumian, P; Gao, H; Garibaldi, F; Gavrilov, G; Geiger, P; Gharibyan, V; Golendukhin, A; Graw, G; Grebeniouk, O; Green, PW; Greeniaus, LG; Grosshauser, C; Gute, A; Gyurjyan, V; Haas, JP; Haeberli, W; Häusser, O; Hansen, J-O; Hasch, D; Henderson, R; Henkes, T; Hertenberger, R; Holler, Y; Holt, RJ; Ihssen, H; Iodice, M; Izotov, A; Jackson, HE; Jgoun, A; Jones, C; Kaiser, R; Kinney, E; Kirsch, M; Kisselev, A; Kitching, P; Königsmann, K; Kolstein, M; Kolster, H; Korsch, W; Kozlov, V; Kramer, LH; Krause, B; Krivokhijine, VG; Kückes, M; Kyle, G; Lachnit, W; Lorenzon, W; Lung, A; Makins, NCR; Manaenkov, SI; Martens, FK; Martin, JW; Mateos, A; Mcllhany, K; McKeown, RD; Meissner, F; Menden, F; Mercer, D; Metz, A; Meyners, N; Mikloukho, O; Miller, CA; Miller, MA; Milner, R; Mitsyn, V; Most, A; Mozzetti, R; Muccifora, V; Nagaitsev, A; Naryshkin, Y; Nathan, AM; Neunreither, F; Niczyporuk, JM; Nowak, W-D; Nupieri, M; Oelwein, P; Ogami, H; O'Neill, TG; Openshaw, R; Ouyang, J; Pate, SF; Pitt, M; Poolman, HR; Potashov, S; Potterveld, DH; Rakness, G; Redwine, R; Reolon, AR; Ristinen, R; Rith, K; Röper, G; Roloff, HO; Rossi, P; Ruh, M; Ryckbosch, D; Sakemi, Y; Savin, I; Schüler, KP; Schwind, A; Shibata, T-A; Shin, T; Simon, A; Sinram, K; Smythe, WR; Sowinski, J; Spengos, M; Steffens, E; Stenger, J; Stewart, J; Stock, F; Stösslein, U; Sutter, M; Tallini, H; Taroian, S; Terkulov, A; Thiessen, DM; Tipton, B; Trudel, A; Tytgat, M; Urciuoli, GM; Brand, JFJVD; Steenhoven, GVD; Vyver, RVD; Vetterli, MC; Vincter, MG; Volk, E; Wander, W; Welch, TP; Williamson, SE; Wise, T; Zapfe, K; Zohrabian, H

Published Date

  • 2000

Published In

Volume / Issue

  • 18 / 2

Start / End Page

  • 303 - 316

International Standard Serial Number (ISSN)

  • 1434-6044