Evidence for a narrow |S| = 1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, V. V. Ammosov, A. Andrus, E. C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, D. Balin, V. Baturin, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H. P. Blok, H. BöttcherA. Borissov, A. Borysenko, M. Bouwhuis, J. Brack, A. Brüll, V. Bryzgalov, G. P. Capitani, T. Chen, X. Chen, H. C. Chiang, G. Ciullo, M. Contalbrigo, P. F. Dalpiaz, W. Deconinck, R. de Leo, L. de Nardo, E. de Sanctis, E. Devitsin, P. di Nezza, M. Düren, M. Ehrenfried, A. Elalaoui-Moulay, G. Elbakian, F. Ellinghaus, U. Elschenbroich, J. Ely, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, B. Fox, S. Frullani, G. Gapienko, V. Gapienko, F. Garibaldi, K. Garrow, E. Garutti, D. Gaskell, G. Gavrilov, V. Gharibyan, G. Graw, O. Grebeniouk, L. G. Greeniaus, I. M. Gregor, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, M. Henoch, R. Hertenberger, W. H.A. Hesselink, A. Hillenbrand, M. Hoek, Y. Holler, B. Hommez, G. Iarygin, A. Ivanilov, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, M. Kopytin, V. Korotkov, V. Kozlov, B. Krauss, V. G. Krivokhijine, L. Lagamba, L. Lapikás, A. Laziev, P. Lenisa, P. Liebing, L. A. Linden-Levy, K. Lipka, W. Lorenzon, H. Lu, J. Lu, S. Lu, X. Lu, B. Q. Ma, B. Maiheu, N. C.R. Makins, Y. Mao, B. Marianski, H. Marukyan, F. Masoli, V. Mexner, N. Meyners, O. Mikloukho, C. A. Miller, Y. Miyachi, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W. D. Nowak, K. Oganessyan, H. Ohsuga, N. Pickert, S. Potashov, D. H. Potterveld, M. Raithel, D. Reggiani, P. E. Reimer, A. Reischl, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, L. Rubacek, J. Rubin, D. Ryckbosch, Y. Salomatin, I. Sanjiev, I. Savin, A. Schäfer, C. Schill, G. Schnell, K. P. Schüler, J. Seele, R. Seidl, B. Seitz, R. Shanidze, C. Shearer, T. A. Shibata, V. Shutov, M. C. Simani, K. Sinram, M. Stancari, M. Statera, E. Steffens, J. J.M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, U. Stösslein, P. Tait, H. Tanaka, S. Taroian, B. Tchuiko, A. Terkulov, A. Tkabladze, A. Trzcinski, M. Tytgat, A. Vandenbroucke, P. van der Nat, G. van der Steenhoven, M. C. Vetterli, V. Vikhrov, M. G. Vincter, C. Vogel, M. Vogt, J. Volmer, C. Weiskopf, J. Wendland, J. Wilbert, G. Ybeles Smit, Y. Ye, Z. Ye, S. Yen, W. Yu, B. Zihlmann, H. Zohrabian, P. Zupranski

Research output: Contribution to journalArticlepeer-review

Abstract

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK0 S→pπ+π-. A peak is observed in the pK0 S invariant mass spectrum at 1528±2.6(stat) ±2.1(syst) MeV. Depending on the background model, the naive statistical significance of the peak is 4-6 standard deviations and its width may be somewhat larger than the experimental resolution of σ=4.3-6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Θ +(uudds̄) pentaquark baryon. No signal for an hypothetical Θ++ baryon was observed in the pK+ invariant mass distribution. The absence of such a signal indicates that an isotensor Θ is excluded and an isovector Θ is unlikely.

Original languageEnglish (US)
Pages (from-to)213-222
Number of pages10
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume585
Issue number3-4
DOIs
StatePublished - Apr 15 2004

Keywords

  • 12.39.Mk
  • 13.60.-r
  • 13.60.Rj
  • 14.20.-c
  • Baryon production
  • Baryons
  • Glueball and nonstandard multi-quark/gluon states
  • Photon and charged-lepton interactions with hadrons

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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