Search for single top quark production in ep collisions at HERA

Summary, in English

A search for single top quark production is performed in e(+/-) pcollisions 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 tugamma 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 (ep --> e t X) = 0.29(-0.14)(+0.15) pb at roots = 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 tugamma coupling k(tugamma) are established at the 95% confidence level.

• Author: A Aktas; V Andreev; T Anthonis; A Asmone; A Babaev; S Backovic; J Bahr; P Baranov; E Barrelet; W Bartel; S Baumgartner; J Becker; M Beckingham; O Behnke; O Behrendt; A Belousov; C Berger; T Berndt; JC Bizot; J Bohme; MO Boenig; V Boudry; J Bracinik; W Braunschweig; V Brisson; HB Broker; DP Brown; D Bruncko; FW Busser; A Bunyatyan; G Buschhorn; L Bystritskaya; AJ Campbell; S Caron; F Cassol-Brunner; V Chekelian; D Clarke; C Collard; JG Contreras; YR Coppens; JA Coughlan; MC Cousinou; BE Cox; G Cozzika; J Cvach; JB Dainton; WD Dau; K Daum; B Delcourt; N Delerue; R Demirchyan; A De Roeck; EA De Wolf; C Diaconu; J Dingfelder; V Dodonov; JD Dowell; A Dubak; C Duprel; G Eckerlin; V Efremenko; S Egli; R Eichler; F Eisele; M Ellerbrock; E Elsen; M Erdmann; W Erdmann; PJW Faulkner; L Favart; A Fedotov; R Felst; J Ferencei; M Fleischer; P Fleischmann; YH Fleming; G Flucke; G Flugge; A Fomenko; I Foresti; J Formanek; 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 Grassler; T Greenshaw; M Gregori; G Grindhammer; D Haidt; L Hajduk; J Haller; G Heinzelmann; RCW Henderson; H Henschel; O Henshaw; R Heremans; G Herrera; I Herynek; M Hildebrandt; KH Hiller; J Hladky; P Hoting; D Hoffmann; R Horisberger; A Hovhannisyan; M Ibbotson; M Jacquet; L Janauschek; X Janssen; V Jemanov; Leif Jönsson; C Johnson; DP Johnson; Hannes Jung; D Kant; M Kapichine; Martin Karlsson; J Katzy; F Keil; N Keller; J Kennedy; IR Kenyon; C Kiesling; M Klein; C Kleinwort; T Kluge; G Knies; B Koblitz; SD Kolya; V Korbel; P Kostka; R Koutouev; A Kropivnitskaya; J Kroseberg; J Kueckens; T Kuhr; MPJ Landon; W Lange; T Lastovicka; P Laycock; A Lebedev; B Leissner; R Lemrani; V Lendermann; S Levonian; B List; E Lobodzinska; N Loktionova; R Lopez-Fernandez; V Lubimov; H Lueders; S Luders; D Luke; L Lytkin; A Makankine; N Malden; E Malinovski; S Mangano; P Marage; J Marks; R Marshall; HU Martyn; J Martyniak; SJ Maxfield; D Meer; A Mehta; K Meier; AB Meyer; H Meyer; J Meyer; S Michine; S Mikocki; D Milstead; F Moreau; A Morozov; JV Morris; K Muller; P Murin; V Nagovizin; B Naroska; J Naumann; T Naumann; PR Newman; F Niebergall; C Niebuhr; D Nikitin; G Nowak; M Nozicka; B Olivier; JE Olsson; D Ozerov; C Pascaud; GD Patel; M Peez; E Perez; A Petrukhin; D Pitzl; R Poschl; B Povh; N Raicevic; J Rauschenberger; P Reimer; B Reisert; C Risler; E Rizvi; P Robmann; R Roosen; A Rostovtsev; S Rusakov; K Rybicki; DPC Sankey; E Sauvan; S Schatzel; J Scheins; FP Schilling; P Schleper; D Schmidt; S Schmidt; S Schmitt; M Schneider; L Schoeffel; A Schoning; V Schroder; HC Schultz-Coulon; C Schwanenberger; K Sedlak; F Sefkow; I Sheviakov; LN 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; PD Thompson; F Tomasz; D Traynor; P Truol; G Tsipolitis; I Tsurin; J Turnau; JE Turney; E Tzamariudaki; A Uraev; M Urban; A Usik; S Valkar; A Valkarova; C Vallee; P Van Mechelen; AV 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; GG Winter; C Wissing; EE Woehrling; E Wunsch; J Zacek; J Zalesak; Z Zhang; A Zhokin; F Zomer; M zur Nedden
• Department/s: Particle and nuclear physics
• Publishing year: 2004
• Language: English
• Pages: 9-22
• Publication/Series: European Physical Journal C. Particles and Fields
• Volume: 33
• Issue: 1
• Links: http://dx.doi.org/10.1140/epjc/s2003-01588-2
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044