Search for single top quark production in ep collisions at HERA

A. Aktas, V. Andreev, T. Anthonis, A. Asmone, A. Babaev, S. Backovic, J. Bähr, P. Baranov, E. Barrelet, W. Bartel, S. Baumgartner, J. Becker, M. Beckingham, O. Behnke, O. Behrendt, A. Belousov, Ch Berger, T. Berndt, J. C. Bizot, J. BöhmeM. O. Boenig, V. Boudry, J. Bracinik, W. Braunschweig, V. Brisson, H. B. Bröker, D. P. Brown, D. Bruncko, F. W. Büsser, A. Bunyatyan, G. Buschhorn, L. Bystritskaya, A. J. Campbell, S. Caron, F. Cassol-Brunner, V. Chekelian, D. Clarke, C. Collard, J. G. Contreras, Y. R. Coppens, J. A. Coughlan, M. C. Cousinou, B. E. Cox, G. Cozzika, J. Cvach, J. B. Dainton, W. D. Dau, K. Daum, B. Delcourt, N. Delerue, R. Demirchyan, A. De Roeck, E. A. De Wolf, C. Diaconu, J. Dingfelder, V. Dodonov, J. D. Dowell, A. Dubak, C. Duprel, G. Eckerlin, V. Efremenko, S. Egli, R. Eichler, F. Eisele, M. Ellerbrock, E. Elsen, M. Erdmann, W. Erdmann, P. J W Faulkner, L. Favart, A. Fedotov, R. Felst, J. Ferencei, M. Fleischer, P. Fleischmann, Y. H. Fleming, G. Flucke, G. Flügge, A. Fomenko, I. Foresti, J. Formánek, G. Franke, G. Frising, E. Gabathuler, K. Gabathuler, J. Garvey, J. Gassner, J. Gayler, R. Gerhards, C. Gerlich, S. Ghazaryan, L. Goerlich, N. Gogitidze, S. Gorbounov, C. Grab, V. Grabski, H. Grässler, T. Greenshaw, M. Gregori, G. Grindhammer, D. Haidt, L. Hajduk, J. Haller, G. Heinzelmann, R. C W Henderson, H. Henschel, O. Henshaw, R. Heremans, G. Herrera, I. Herynek, M. Hildebrandt, K. H. Hiller, J. Hladký, P. Höting, D. Hoffmann, R. Horisberger, A. Hovhannisyan, M. Ibbotson, M. Jacquet, L. Janauschek, X. Janssen, V. Jemanov, L. Jönsson, C. Johnson, D. P. Johnson, H. Jung, D. Kant, M. Kapichine, M. Karlsson, J. Katzy, F. Keil, N. Keller, J. Kennedy, I. R. Kenyon, C. Kiesling, M. Klein, C. Kleinwort, T. Kluge, G. Knies, B. Koblitz, S. D. Kolya, V. Korbel, P. Kostka, R. Koutouev, A. Kropivnitskaya, J. Kroseberg, J. Kueckens, T. Kuhr, M. P J Landon, W. Lange, T. Laštovička, P. Laycock, A. Lebedev, B. Leibner, R. Lemrani, V. Lendermann, S. Levonian, B. List, E. Lobodzinska, N. Loktionova, R. Lopez-Fernandez, V. Lubimov, H. Lueders, S. Läders, D. Lüke, L. Lytkin, A. Makankine, N. Malden, E. Malinovski, S. Mangano, P. Marage, J. Marks, R. Marshall, H. U. Martyn, J. Martyniak, S. J. Maxfield, D. Meer, A. Mehta, K. Meier, A. B. Meyer, H. Meyer, J. Meyer, S. Michine, S. Mikocki, D. Milstead, F. Moreau, A. Morozov, J. V. Morris, K. Müller, P. Murín, V. Nagovizin, B. Naroska, J. Naumann, Th Naumann, P. R. Newman, F. Niebergall, C. Niebuhr, D. Nikitin, G. Nowak, M. Nozicka, B. Olivier, J. E. Olsson, D. Ozerov, C. Pascaud, G. D. Patel, M. Peez, E. Perez, A. Petrukhin, D. Pitzl, R. Pöschl, B. Povh, N. Raicevic, J. Rauschenberger, P. Reimer, B. Reisert, C. Risler, E. Rizvi, P. Robmann, R. Roosen, A. Rostovtsev, S. Rusakov, K. Rybicki, D. P C Sankey, E. Sauvan, S. Schatzel, J. Scheins, F. P. Schilling, P. Schleper, D. Schmidt, S. Schmidt, S. Schmitt, M. Schneider, L. Schoeffel, A. Schöning, V. Schröder, H. C. Schultz-Coulon, C. Schwanenberger, K. Sedlák, F. Sefkow, I. Sheviakov, L. N. Shtarkov, Y. Sirois, T. Sloan, P. Smirnov, Y. Soloviev, D. South, V. Spaskov, A. Specka, H. Spitzer, R. Stamen, B. Stella, J. Stiewe, I. Strauch, U. Straumann, G. Thompson, P. D. Thompson, F. Tomasz, D. Traynor, P. Truöl, G. Tsipolitis, I. Tsurin, J. Turnau, J. E. Turney, E. Tzamariudaki, A. Uraev, M. Urban, A. Usik, S. Valkár, A. Valkárová, C. Vallée, P. Van Mechelen, A. Vargas Trevino, S. Vassiliev, Y. Vazdik, C. Veelken, A. Vest, A. Vichnevski, V. Volchinski, K. Wacker, J. Wagner, B. Waugh, G. Weber, R. Weber, D. Wegener, C. Werner, N. Werner, M. Wessels, B. Wessling, M. Winde, G. G. Winter, Ch Wissing, E. E. Woehrling, E. Wunsch, J. Žáček, J. Zálešák, Z. Zhang, A. Zhokin, F. Zomer, M. Zur Nedden

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A search for single top quark production is performed in e ±p collisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb-1. A model for the anomalous production of top quarks in a flavour changing neutral current process involving a tuγ coupling is investigated. Decays of top quarks into a b quark and a W boson are considered in the leptonic and the hadronic decay channels of the W. Both a cut-based analysis and a multivariate likelihood analysis are performed to discriminate anomalous top quark production from Standard Model background processes. In the leptonic channel, 5 events are found while 1.31 ± 0.22 events are expected from the Standard Model background. In the hadronic channel, no excess above the expectation for Standard Model processes is found. These observations lead to a cross section σ (ep → etX) = 0.29-0.14+0.15 pb at 97 √s = 319 GeV. Alternatively, assuming that the observed events are due to a statistical fluctuation, upper limits of 0.55 pb on the anomalous top production cross section and of 0.27 on the tuγ coupling κ tuγ are established at the 95% confidence level.
    Original languageEnglish
    Pages (from-to)9-22
    Number of pages13
    JournalEuropean Physical Journal C
    Volume33
    Issue number1
    DOIs
    Publication statusPublished - Mar 2004

    Keywords

    • Electron collisions (search for single top quark prodn. in ep collisions at HERA); Gamma ray interactions (tug coupling)

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