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Elastic and proton-dissociative ρ0 photoproduction at HERA

  • J. Breitweg
  • , M. Derrick
  • , D. Krakauer
  • , S. Magill
  • , D. Mikunas
  • , B. Musgrave
  • , J. Repond
  • , R. Stanek
  • , R. L. Talaga
  • , R. Yoshida
  • , H. Zhang
  • , M. C.K. Mattingly
  • , F. Anselmo
  • , P. Antonioli
  • , G. Bari
  • , M. Basile
  • , L. Bellagamba
  • , D. Boscherini
  • , A. Bruni
  • , G. Bruni
  • G. Cara Romeo, G. Castellini, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. de Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam, R. Nania, C. Nemoz, F. Palmonari, A. Pesci, A. Polini, F. Ricci, G. Sartorelli, Y. Zamora Garcia, A. Zichichi, C. Amelung, A. Bornheim, I. Brock, K. Coböken, J. Crittenden, R. Deffner, M. Eckert, M. Grothe, H. Hartmann, K. Heinloth, L. Heinz, E. Hilger, H. P. Jakob, U. F. Katz, R. Kerger, E. Paul, M. Pfeiffer, Ch Rembser, J. Stamm, R. Wedemeyer, H. Wieber, D. S. Bailey, S. Campbell-Robson, W. N. Cottingham, B. Foster, R. Hall-Wilton, M. E. Hayes, G. P. Heath, H. F. Heath, J. D. McFall, D. Piccioni, D. G. Roff, R. J. Tapper, M. Arneodo, R. Ayad, M. Capua, A. Garfagnini, L. Iannotti, M. Schioppa, G. Susinno, J. Y. Kim, J. H. Lee, I. T. Lim, M. Y. Pac, A. Caldwell, N. Cartiglia, Z. Jing, W. Liu, B. Mellado, J. A. Parsons, S. Ritz, S. Sampson, F. Sciulli, P. B. Straub, Q. Zhu, P. Borzemski, J. Chwastowski, A. Eskreys, J. Figiel, K. Klimek, M. B. Przybycień, L. Zawiejski, L. Adamczyk, B. Bednarek, M. Bukowy, A. Czermak, K. Jeleń, D. Kisielewska, T. Kowalski, E. Rulikowska-Zarebska, L. Suszycki, J. Zaja̧c, Z. Dulinński, A. Kotanński, G. Abbiendi, L. A.T. Bauerdick, U. Behrens, H. Beier, J. K. Bienlein, G. Cases, O. Deppe, K. Desler, G. Drews, U. Fricke, D. J. Gilkinson, C. Glasman, P. Göttlicher, T. Haas, W. Hain, D. Hasell, K. F. Johnson, M. Kasemann, W. Koch, U. Kötz, H. Kowalski, J. Labs, L. Lindemann, B. Löhr, M. Löwe, O. Mańczak, J. Milewski, T. Monteiro, J. S.T. Ng, D. Notz, K. Ohrenberg, I. H. Park, A. Pellegrino, F. Pelucchi, K. Piotrzkowski, M. Roco, M. Rohde, J. Roldán, J. J. Ryan, A. A. Savin, U. Schneekloth, O. Schwarzer, F. Selonke, B. Surrow, E. Tassi, T. Voß, D. Westphal, G. Wolf, U. Wollmer, C. Youngman, A. F. Zarnecki, W. Zeuner, B. D. Burow, H. J. Grabosch, A. Meyer, S. Schlenstedt, G. Barbagli, E. Gallo, P. Pelfer, G. Anzivino, G. Maccarrone, L. Votano, A. Bamberger, S. Eisenhardt, P. Markun, T. Trefzger, S. Wölfle, J. T. Bromley, N. H. Brook, P. J. Bussey, A. T. Doyle, N. Macdonald, D. H. Saxon, L. E. Sinclair, E. Strickland, R. Waugh, I. Bohnet, N. Gendner, U. Holm, A. Meyer-Larsen, H. Salehi, K. Wick, L. K. Gladilin, D. Horstmann, D. Kçira, R. Klanner, E. Lohrmann, G. Poelz, W. Schott, F. Zetsche, T. C. Bacon, I. Butterworth, J. E. Cole, G. Howell, B. H.Y. Hung, L. Lamberti, K. R. Long, D. B. Miller, N. Pavel, A. Prinias, J. K. Sedgbeer, D. Sideris, R. Walker, U. Mallik, S. M. Wang, J. T. Wu, P. Cloth, D. Filges, J. I. Fleck, T. Ishii, M. Kuze, I. Suzuki, K. Tokushuku, S. Yamada, K. Yamauchi, Y. Yamazaki, S. J. Hong, S. B. Lee, S. W. Nam, S. K. Park, F. Barreiro, J. P. Fernández, G. García, R. Graciani, J. M. Hernández, L. Hervás, L. Labarga, M. Martínez, J. del Peso, J. Puga, J. Terrón, J. F. de Trocóniz, F. Corriveau, D. S. Hanna, J. Hartmann, L. W. Hung, W. N. Murray, A. Ochs, M. Riveline, D. G. Stairs, M. St-Laurent, R. Ullmann, T. Tsurugai, V. Bashkirov, B. A. Dolgoshein, A. Stifutkin, G. L. Bashindzhagyan, P. F. Ermolov, Y. A. Golubkov, L. A. Khein, N. A. Korotkova, I. A. Korzhavina, V. A. Kuzmin, O. Y. Lukina, A. S. Proskuryakov, L. M. Shcheglova, A. N. Solomin, S. A. Zotkin, C. Bokel, M. Botje, N. Brümmer, F. Chlebana, J. Engelen, E. Koffeman, P. Kooijman, A. van Sighem, H. Tiecke, N. Tuning, W. Verkerke, J. Vossebeld, M. Vreeswijk, L. Wiggers, E. de Wolf, D. Acosta, B. Bylsma, L. S. Durkin, J. Gilmore, C. M. Ginsburg, C. L. Kim, T. Y. Ling, P. Nylander, T. A. Romanowski, H. E. Blaikley, R. J. Cashmore, A. M. Cooper-Sarkar, R. C.E. Devenish, J. K. Edmonds, J. Große-Knetter, N. Harnew, C. Nath, V. A. Noyes, A. Quadt, O. Ruske, J. R. Tickner, H. Uijterwaal, R. Walczak, D. S. Waters, A. Bertolin, R. Brugnera, R. Carlin, F. Dal Corso, U. Dosselli, S. Limentani, M. Morandin, M. Posocco, L. Stanco, R. Stroili, C. Voci, J. Bulmahn, B. Y. Oh, J. R. Okrasiński, W. S. Toothacker, J. J. Whitmore, Y. Iga, G. D'Agostini, G. Marini, A. Nigro, M. Raso, J. C. Hart, N. A. McCubbin, T. P. Shah, E. Barberis, D. Epperson, C. Heusch, J. T. Rahn, H. F.W. Sadrozinski, A. Seiden, R. Wichmann, D. C. Williams, H. Abramowicz, G. Briskin, S. Dagan, S. Kananov, A. Levy, T. Abe, T. Fusayasu, M. Inuzuka, K. Nagano, K. Umemori, T. Yamashita, R. Hamatsu, T. Hirose, K. Homma, S. Kitamura, T. Matsushita, R. Cirio, M. Costa, M. I. Ferrero, S. Maselli, V. Monaco, C. Peroni, M. C. Petrucci, M. Ruspa, R. Sacchi, A. Solano, A. Staiano, M. Dardo, D. C. Bailey, C. P. Fagerstroem, R. Galea, G. F. Hartner, K. K. Joo, G. M. Levman, J. F. Martin, R. S. Orr, S. Polenz, A. Sabetfakhri, D. Simmons, R. J. Teuscher, J. M. Butterworth, C. D. Catterall, T. W. Jones, J. B. Lane, R. L. Saunders, M. R. Sutton, M. Wing, J. Ciborowski, G. Grzelak, M. Kasprzak, K. Muchorowski, R. J. Nowak, J. M. Pawlak, R. Pawlak, T. Tymieniecka, A. K. Wróblewski, J. A. Zakrzewski, M. Adamus, C. Coldewey, Y. Eisenberg, D. Hochman, U. Karshon, W. F. Badgett, D. Chapin, R. Cross, S. Dasu, C. Foudas, R. J. Loveless, S. Mattingly, D. D. Reeder, W. H. Smith, A. Vaiciulis, M. Wodarczyk, A. Deshpande, S. Dhawan, V. W. Hughes, S. Bhadra, W. R. Frisken, M. Khakzad, W. B. Schmidke
  • Argonne National Laboratory
  • Andrews University
  • University of Bologna
  • IROE Florence
  • University of Salerno
  • University of Crete
  • European Synchrotron Radiation Facility
  • University of Bonn
  • CERN
  • University of Bristol
  • University of Calabria
  • University of Turin
  • Chonnam National University
  • Dongshin University
  • Columbia University
  • German Electron Synchrotron
  • Institute of Nuclear Physics
  • AGH University of Krakow
  • Jagiellonian University in Kraków
  • SAP Research
  • Florida State University
  • Nokia
  • Kyungpook National University
  • Fermi National Accelerator Laboratory
  • NORCOM Infosystems
  • University of Oxford
  • University of Florence
  • National Institute for Nuclear Physics
  • University of Perugia
  • University of Freiburg
  • Ludwig Maximilian University of Munich
  • University of Glasgow
  • University of Hamburg
  • Imperial College London
  • University of Iowa
  • Jülich Research Centre
  • High Energy Accelerator Research Organization, Institute of Particle and Nuclear Physics
  • The University of Osaka
  • Korea University
  • Wayne State University
  • Universidad Autónoma de Madrid
  • McGill University
  • Meiji Gakuin University
  • Moscow Engineering Physics Institute
  • Lomonosov Moscow State University
  • University of Amsterdam
  • Ohio State University
  • United States Department of Energy
  • University of Padua
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  • Polytechnic University Japan
  • University of Rome La Sapienza
  • STFC Rutherford Appleton Laboratory
  • University of California at Santa Cruz
  • Lawrence Berkeley National Laboratory
  • Tel Aviv University
  • The University of Tokyo
  • Tokyo Metropolitan University
  • Tokyo Metropolitan College of Industrial Technology
  • University of Toronto
  • University College London
  • University of Warsaw
  • Institute of Nuclear Chemistry and Technology, Warsaw
  • Weizmann Institute of Science
  • University of Wisconsin-Madison
  • Yale University
  • York University Toronto

Research output: Contribution to journalArticlepeer-review

135 Scopus citations

Abstract

Elastic and proton-dissociative ρ0 photoproduction (γp → p0p, γp → ρ0N, respectively, with p0 → π+π-) has been studied in ep interactions at HERA for photon-proton centre-of-mass energies in the range 50 < W < 100 GeV and for |t| < 0.5 GeV2, where t is the square of the four-momentum transfer at the proton vertex; the results on the proton-dissociative reaction are presented for masses of the dissociated proton system in the range M2 N < 0.1W2. For the elastic process, the π+π- invariant mass spectrum has been investigated as a function of t. As in fixed target experiments, the ρ0 resonance shape is asymmetric; this asymmetry decreases with increasing |t|, as expected in models in which the asymmetry is ascribed to the interference of resonant and non-resonant π+π- production. The cross section has been studied as a function of W; a fit to the resonant part with the form Wa gives a = 0.16 ± 0.06 (stat.) +0.11 -0.15 (syst.). The resonant part of the γp → π+π-p cross section is 11.2 ± 0.1 (stat.) +1.1 -1.2 (syst.) μb at 〈W〉 = 71.7 GeV. The t dependence of the cross section can be described by a function of the type Aρ exp (-bρ|t| + cρt2) with bρ = 10.9 ± 0.3 (stat.) +1.0 -0.5 (syst.) GeV-2 and cρ = 2.7 ± 0.9 (stat.) +1.9 -1.7 (syst.) GeV-4. The t dependence has also been studied as a function of W and a value of the slope of the pomeron trajectory α IP′ = 0.23 ± 0.15 (stat.) +0.10 -0.07 (syst.) GeV-2 has been deduced. The ρ0 spin density matrix elements r04 00 r04 1-1 and ℜe[r04 10] have been measured and found to be consistent with expectations based on s-channel helicity conservation. For proton-dissociative π+π- photoproduction in the ρ0 mass range, the distributions of the two-pion invariant mass, W and the polar and azimuthal angles of the pions in the helicity frame are the same within errors as those for the elastic process. The t distribution has been fitted to an exponential function with a slope parameter 5.8 ± 0.3 (stat.) ± 0.5 (syst.) GeV-2. The ratio of the elastic to proton-dissociative ρ0 photoproduction cross section is 2.0 ± 0.2 (stat.) ± 0.7 (syst.).

Original languageEnglish
Pages (from-to)247-267
Number of pages21
JournalEuropean Physical Journal C
Volume2
Issue number2
DOIs
StatePublished - 1998

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