Eur. Phys. J. C (2011) 71: 1555
https://doi.org/10.1140/epjc/s10052-011-1555-z

Regular Article - Experimental Physics

Search for single top quark production via contact interactions at LEP2

¹ Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011-3160, USA
² Physics Department, Universiteit Antwerpen, Universiteitsplein 1, 2610, Antwerpen, Belgium
³ IIHE, ULB-VUB, Pleinlaan 2, 1050, Brussels, Belgium
⁴ Physics Laboratory, University of Athens, Solonos Str. 104, 10680, Athens, Greece
⁵ Department of Physics, University of Bergen, Allégaten 55, 5007, Bergen, Norway
⁶ Dipartimento di Fisica, Università di Bologna and INFN, Viale C. Berti Pichat 6/2, 40127, Bologna, Italy
⁷ Centro Brasileiro de Pesquisas Físicas, rua Xavier Sigaud 150, 22290, Rio de Janeiro, Brazil
⁸ Inst. de Física, Univ. Estadual do Rio de Janeiro, rua São Francisco Xavier 524, Rio de Janeiro, Brazil
⁹ Collège de France, Lab. de Physique Corpusculaire, IN2P3-CNRS, 75231, Paris Cedex 05, France
¹⁰ CERN, 1211, Geneva 23, Switzerland
¹¹ Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, IN2P3-CNRS, BP28, 67037, Strasbourg Cedex 2, France
¹² Institute of Nuclear Physics, N.C.S.R. Demokritos, P.O. Box 60228, 15310, Athens, Greece
¹³ FZU, Inst. of Phys. of the C.A.S. High Energy Physics Division, Na Slovance 2, 182 21, Praha 8, Czech Republic
¹⁴ Dipartimento di Fisica, Università di Genova and INFN, Via Dodecaneso 33, 16146, Genova, Italy
¹⁵ Institut des Sciences Nucléaires, IN2P3-CNRS, Université de Grenoble 1, 38026, Grenoble Cedex, France
¹⁶ Helsinki Institute of Physics and Department of Physical Sciences, P.O. Box 64, 00014, University of Helsinki, Finland
¹⁷ Joint Institute for Nuclear Research, Dubna, Head Post Office, P.O. Box 79, 101 000, Moscow, Russian Federation
¹⁸ Institut für Experimentelle Kernphysik, Universität Karlsruhe, Postfach 6980, 76128, Karlsruhe, Germany
¹⁹ Institute of Nuclear Physics PAN, Ul. Radzikowskiego 152, 31142, Krakow, Poland
²⁰ Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, 30055, Krakow, Poland
²¹ LAL, Univ. Paris-Sud, CNRS/IN2P3, Orsay, France
²² School of Physics and Chemistry, University of Lancaster, Lancaster, LA1 4YB, UK
²³ LIP, FCUL, IST, CFC-UC, Av. Elias Garcia, 14-1°, 1000, Lisboa Codex, Portugal
²⁴ Department of Physics, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX, UK
²⁵ Department of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ, UK
²⁶ LPNHE, IN2P3-CNRS, Univ. Paris VI et VII, Tour 33 (RdC), 4 place Jussieu, 75252, Paris Cedex 05, France
²⁷ Department of Physics, University of Lund, Sölvegatan 14, 223 63, Lund, Sweden
²⁸ Université Claude Bernard de Lyon, IPNL, IN2P3-CNRS, 69622, Villeurbanne Cedex, France
²⁹ Dipartimento di Fisica, Università di Milano and INFN-MILANO, Via Celoria 16, 20133, Milan, Italy
³⁰ Dipartimento di Fisica, Università di Milano-Bicocca and INFN-MILANO, Piazza della Scienza 3, 20126, Milan, Italy
³¹ IPNP of MFF, Charles University, Areal MFF, V Holesovickach 2, 180 00, Praha 8, Czech Republic
³² NIKHEF, Postbus 41882, 1009 DB, Amsterdam, The Netherlands
³³ National Technical University, Physics Department, Zografou Campus, 15773, Athens, Greece
³⁴ Physics Department, University of Oslo, Blindern, 0316, Oslo, Norway
³⁵ Departamento de la Fisica, Universidad Oviedo, Avda. Calvo Sotelo s/n, 33007, Oviedo, Spain
³⁶ Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
³⁷ Dipartimento di Fisica, Università di Padova and INFN, Via Marzolo 8, 35131, Padua, Italy
³⁸ Rutherford Appleton Laboratory, Chilton, Didcot, OX11 OQX, UK
³⁹ Dipartimento di Fisica, Università di Roma II and INFN, Tor Vergata, 00173, Rome, Italy
⁴⁰ Dipartimento di Fisica, Università di Roma III and INFN, Via della Vasca Navale 84, 00146, Rome, Italy
⁴¹ DAPNIA/Service de Physique des Particules, CEA-Saclay, 91191, Gif-sur-Yvette Cedex, France
⁴² Instituto de Fisica de Cantabria (CSIC-UC), Avda. los Castros s/n, 39006, Santander, Spain
⁴³ Institute for High Energy Physics, Serpukov P.O. Box 35, Protvino, Moscow Region, Russian Federation
⁴⁴ J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
⁴⁵ Laboratory for Astroparticle Physics, University of Nova Gorica, Kostanjeviska 16a, 5000, Nova Gorica, Slovenia
⁴⁶ Department of Physics, University of Ljubljana, 1000, Ljubljana, Slovenia
⁴⁷ Fysikum, Stockholm University, Box 6730, 113 85, Stockholm, Sweden
⁴⁸ Dipartimento di Fisica Sperimentale, Università di Torino and INFN, Via P. Giuria 1, 10125, Turin, Italy
⁴⁹ INFN, Sezione di Torino and Dipartimento di Fisica Teorica, Università di Torino, Via Giuria 1, 10125, Turin, Italy
⁵⁰ Dipartimento di Fisica, Università di Trieste and INFN, Via A. Valerio 2, 34127, Trieste, Italy
⁵¹ Istituto di Fisica, Università di Udine and INFN, 33100, Udine, Italy
⁵² Univ. Federal do Rio de Janeiro, C.P. 68528 Cidade Univ., Ilha do Fundão, 21945-970, Rio de Janeiro, Brazil
⁵³ Department of Radiation Sciences, University of Uppsala, P.O. Box 535, 751 21, Uppsala, Sweden
⁵⁴ IFIC, Valencia-CSIC, and D.F.A.M.N., U. de Valencia, Avda. Dr. Moliner 50, 46100, Burjassot (Valencia), Spain
⁵⁵ Institut für Hochenergiephysik, Österr. Akad. d. Wissensch., Nikolsdorfergasse 18, 1050, Vienna, Austria
⁵⁶ Institute Nuclear Studies and University of Warsaw, Ul. Hoza 69, 00681, Warsaw, Poland
⁵⁷ Fachbereich Physik, University of Wuppertal, Postfach 100 127, 42097, Wuppertal, Germany

^* e-mail: timmerma@mail.cern.ch

Received: 27 September 2010
Revised: 7 December 2010
Published online: 15 February 2011

Abstract

Single top quark production via four-fermion contact interactions associated to flavour-changing neutral currents was searched for in data taken by the DELPHI detector at LEP2. The data were accumulated at centre-of-mass energies ranging from 189 to 209 GeV, with an integrated luminosity of 598.1 pb⁻¹. No evidence for a signal was found. Limits on the energy scale Λ, were set for scalar-, vector- and tensor-like coupling scenarios.