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arXiv · 1412.7317

Pentaquark $Θ^+$ search at HERMES

The HERMES Collaboration·N. Akopov·Z. Akopov·W. Augustyniak·R. Avakian·A. Avetissian·E. Avetisyan·S. Belostotski·H. P. Blok·A. Borissov·J. Bowles·V. Bryzgalov·J. Burns·G. P. Capitani·E. Cisbani·G. Ciullo·M. Contalbrigo·P. F. Dalpiaz·W. Deconinck·R. De Leo·E. De Sanctis·P. Di Nezza·G. Elbakian·E. Etzelmüller·R. Fabbri·A. Fantoni·L. Felawka·S. Frullani·D. Gabbert·J. Garay García·F. Garibaldi·G. Gavrilov·F. Giordano·S. Gliske·M. Hartig·D. Hasch·Y. Holler·I. Hristova·Y. Imazu·A. Ivanilov·H. E. Jackson·S. Joosten·R. Kaiser·G. Karyan·T. Keri·E. Kinney·A. Kisselev·V. Kozlov·P. Kravchenko·V. G. Krivokhijine·L. Lagamba·L. Lapikás·I. Lehmann·A. López Ruiz·W. Lorenzon·X. Lu·B. -Q. Ma·D. Mahon·S. I. Manaenkov·Y. Mao·B. Marianski·A. Martinez de la Ossa·H. Marukyan·C. A. Miller·Y. Miyachi·A. Movsisyan·M. Murray·E. Nappi·A. Nass·M. Negodaev·W. -D. Nowak·L. L. Pappalardo·R. Perez-Benito·A. Petrosyan·P. E. Reimer·A. R. Reolon·C. Riedl·K. Rith·G. Rosner·A. Rostomyan·J. Rubin·D. Ryckbosch·Y. Salomatin·G. Schnell·K. P. Schüler·B. Seitz·T. -A. Shibata·M. Stancari·J. J. M. Steijger·S. Taroian·A. Terkulov·R. Truty·A. Trzcinski·M. Tytgat·Y. Van Haarlem·C. Van Hulse·D. Veretennikov·V. Vikhrov·I. Vilardi·S. Wang
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Abstract

The earlier search at HERMES for narrow baryon states excited in quasi-real photoproduction, decaying through the channel $pK_S^0\rightarrow pπ^+π^-$, has been extended with improved decay-particle reconstruction, more advanced particle identification, and increased event samples. The structure observed earlier at an invariant mass of 1528 MeV shifts to 1522 MeV and the statistical significance drops to about 2$σ$ for data taken with a deuterium target. The number of events above background is $68_{-31}^{+98}\text{(stat)}\pm13\text{(sys)}$. No such structure is observed in the hydrogen data set.

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The HERMES Collaboration, N. Akopov, Z. Akopov, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetisyan, S. Belostotski, H. P. Blok, A. Borissov, J. Bowles, V. Bryzgalov, J. Burns, G. P. Capitani, E. Cisbani, G. Ciullo, M. Contalbrigo, P. F. Dalpiaz, W. Deconinck, R. De Leo, E. De Sanctis, P. Di Nezza, G. Elbakian, E. Etzelmüller, R. Fabbri, A. Fantoni, L. Felawka, S. Frullani, D. Gabbert, J. Garay García, F. Garibaldi, G. Gavrilov, F. Giordano, S. Gliske, M. Hartig, D. Hasch, Y. Holler, I. Hristova, Y. Imazu, A. Ivanilov, H. E. Jackson, S. Joosten, R. Kaiser, G. Karyan, T. Keri, E. Kinney, A. Kisselev, V. Kozlov, P. Kravchenko, V. G. Krivokhijine, L. Lagamba, L. Lapikás, I. Lehmann, A. López Ruiz, W. Lorenzon, X. Lu, B. -Q. Ma, D. Mahon, S. I. Manaenkov, Y. Mao, B. Marianski, A. Martinez de la Ossa, H. Marukyan, C. A. Miller, Y. Miyachi, A. Movsisyan, M. Murray, E. Nappi, A. Nass, M. Negodaev, W. -D. Nowak, L. L. Pappalardo, R. Perez-Benito, A. Petrosyan, P. E. Reimer, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, J. Rubin, D. Ryckbosch, Y. Salomatin, G. Schnell, K. P. Schüler, B. Seitz, T. -A. Shibata, M. Stancari, J. J. M. Steijger, S. Taroian, A. Terkulov, R. Truty, A. Trzcinski, M. Tytgat, Y. Van Haarlem, C. Van Hulse, D. Veretennikov, V. Vikhrov, I. Vilardi, S. Wang. 2015-04-27. Pentaquark $Θ^+$ search at HERMES. https://doi.org/10.1103/physrevd.91.057101

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