Eur. Phys. J. C (1998) 1: 1-20
https://doi.org/10.1007/BF01245794

Search for charginos, neutralinos and gravitinos at LEP

⁴² Department of Physics and Astronomy, Iowa State University, 50011-3160, Ames, IA, USA
²⁵ Physics Department, Univ. Instelling Antwerpen, Universiteitsplein 1, B-2610, Wilrijk, Belgium
⁵⁶ IIHE, ULB-VUB, Pleinlaan 2, B-1050, Brussels, Belgium
⁵⁷ Faculty des Sciences, Univ. de l'Etat Mons, Av. Maistriau 19, B-7000, Mons, Belgium
⁵⁰ Physics Laboratory, University of Athens, Solonos Str. 104, GR-10680, Athens, Greece
²⁸ Department of Physics, University of Bergen, Allégaten 55, N-5007, Bergen, Norway
²⁴ Dipartimento di Fisica, University di Bologna and INFN, Via Irnerio 46, I-40126, Bologna, Italy
²² Centro Brasileiro de Pesquisas Físicas, rua Xavier Sigaud 150, RJ-22290, Rio de Janeiro, Brazil
⁵² Depto. de Física, Pont. Univ. Católica, C.P. 38071, RJ-22453, Rio de Janeiro, Brazil
⁵³ Inst. de Fisica, Univ. Estadual do Rio de Janeiro, rua Sao Francisco Xavier 524, Rio de Janeiro, Brazil
³⁶ Faculty of Mathematics and Physics, Comenius University, Mlynska Dolina, SK-84215, Bratislava, Slovakia
²³ Lab. de Physique Corpusculaire, IN2P3-CNRS, College de France, F-75231, Paris Cedex 05, France
⁹ CERN, CH-1211 Geneva 23, Switzerland
⁴⁷ Institut de Recherches Subatomiques, IN2P3 - CNRS/ULP - BP20, F-67037, Strasbourg Cedex, France
⁴⁹ Institute of Nuclear Physics, N.C.S.R. Demokritos, P.O. Box 60228, GR-15310, Athens, Greece
⁵¹ FZU, Inst. of Physics of the C.A.S. High Energy Physics Division, Na Slovance 2, 180 40, Praha 8, Czech Republic
³⁰ Dipartimento di Fisica, University di Genova and INFN, Via Dodecaneso 33, I-16146, Genova, Italy
¹³ Institut des Sciences Nucléaires, IN2P3-CNRS, Université de Grenoble 1, F-38026, Grenoble Cedex, France
¹⁸ Helsinki Institute of Physics, HIP, P.O. Box 9, FIN-00014, Helsinki, Finland
⁵ Joint Institute for Nuclear Research, Dubna, Head Post Office, P.O. Box 79, 101 000, Moscow, Russian Federation
¹² Institut fur Experimentelle Kernphysik, Universität Karlsruhe, Postfach 6980, D-76128, Karlsruhe, Germany
³² Institute of Nuclear Physics and University of Mining and Metalurgy, Ul. Kawiory 26a, PL-30055, Krakow, Poland
¹⁶ Lab. de l'Accélérateur Linéaire, Université de Paris-Sud, IN2P3-CNRS Bat. 200, F-91405, Orsay Cedex, France
⁵⁴ School of Physics and Chemistry, University of Lancaster, LA1 4YB, Lancaster, UK
¹ LIP, IST, FOUL - Av. Elias Garcia, 14-10, P-1000, Lisboa Codex, Portugal
⁷ Department of Physics, University of Liverpool, P.O. Box 147, L69 3BX, Liverpool, UK
¹⁹ LPNHE, IN2P3-CNRS, Universités Paris VI et VII, Tour 33 (RdC), 4 place Jussieu, F-75252, Paris Cedex 05, France
⁸ Department of Physics, University of Lund, Sölvegatan 14, S-22363, Lund, Sweden
¹⁴ Université Claude Bernard de Lyon, IPNL, IN2P3-CNRS, F-69622, Villeurbanne Cedex, France
⁴⁴ Univ. d'Aix - Marseille II - CPP, IN2P3-CNRS, F-13288, Marseille Cedex 09, France
²⁷ Dipartimento di Fisica, Universitè di Milano and INFN, Via Celoria 16, I-20133, Milan, Italy
⁴³ Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen 0, Denmark
³⁷ NC, Nuclear Centre of MFF, Charles University, Areal MFF, V Holesovickach 2, 180 00, Praha 8, Czech Republic
¹⁵ NIKHEF, Postbus 41882, NL-1009 DB, Amsterdam, The Netherlands
⁴⁸ Physics Department, Zografou Campus, National Technical University, GR-15773, Athens, Greece
³³ Physics Department, University of Oslo, Oslo 3, N-1000, Blindern, Norway
¹⁷ Dpto. Fisica, Univ. Oviedo, Avda. Calvo Sotelo, (CICYT-AEN96-1681), S/N-33007, Oviedo, Spain
⁴⁵ Department of Physics, University of Oxford, Keble Road, OX1 3RH, Oxford, UK
³¹ Dipartimento di Fisica, University di Padova and INFN, Via Marzolo 8, I-35131, Padua, Italy
³ Rutherford Appleton Laboratory, OX11 OQX, Chilton, Didcot, UK
³⁵ Dipartimento di Fisica, Università di Roma II and INFN, Tor Vergata, I-00173, Rome, Italy
²⁰ CEA, DAPNIA/Service de Physique des Particules, CE-Saclay, F-91191, Gif-sur-Yvette Cedex, France
³⁴ Instituto de Fisica de Cantabria (CSIC-UC), Avda. los Castros, S/N-39006, Santander, Spain
⁴ Inst. for High Energy Physics, Serpukov P.O. Box 35, Protvino, (Moscow Region), Russian Federation
³⁸ J. Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia
³⁹ Department of Astroparticle Physics, School of Environmental Sciences, Kostanjeviska 16a, SI-5000, Nova Gorica, Slovenia
⁴⁰ Department of Physics, University of Ljubljana, SI-1000, Ljubljana, Slovenia
¹¹ Fysikum, Stockholm University, Box 6730, S-113 85, Stockholm, Sweden
²⁶ Dipartimento di Fisica Sperimentale, University di Torino and INFN, Via P. Giuria 1, I-10125, Turin, Italy
⁴¹ Dipartimento di Fisica, University di Trieste and INFN, Via A. Valerio 2, I-34127, Trieste, Italy
⁵⁵ Istituto di Fisica, University di Udine, I-33100, Udine, Italy
¹⁰ Univ. Federal do Rio de Janeiro, C.P. 68528 Cidade Univ., Ilha do Fundão, BR-21945-970, Rio de Janeiro, Brazil
²⁹ Department of Radiation Sciences, University of Uppsala, P.O. Box 535, S-751 21, Uppsala, Sweden
⁶ IFIC, Valencia-CSIC, and D.F.A.M.N., U. de Valencia, Avda. Dr. Moliner 50, E-46100, Burjassot (Valencia), Spain
² Institut fur Hochenergiephysik, Österr. Akad. d. Wissensch., Nikolsdorfergasse 18, A-1050, Vienna, Austria
⁴⁶ Inst. Nuclear Studies and University of Warsaw, Ul. Hoza 69, PL-00681, Warsaw, Poland
²¹ Fachbereich Physik, University of Wuppertal, Postfach 100 127, D-42097, Wuppertal, Germany

Received: 8 August 1997
Published online: 27 February 2005

Abstract

An update of the searches for charginos and neutralinos in DELPHI is presented, based mainly on recent data collected at centre-of-mass energies of 161 GeV and 172 GeV. No signal is found. For a sneutrino with mass above 300 GeV/c ² and a mass difference between the chargino and the lightest neutralino above 10 GeV/c ², the lower limit at 95% confidence level on the chargino mass ranges from 84.3 GeV/c ² to the kinematical limit (86.0 GeV/c ²), depending on the mixing parameters. The limit decreases for lower chargino-neutralino mass differences. The limit in the case of a light sneutrino is 67.6 GeV/c ², provided that that there is no light sneutrino with a mass within 10 GeV/c ² below the chargino mass. Upper limits on neutralino pair production cross-sections of about a picobarn are derived. The (μ,M ²) domain excluded in the MSSM-GUT scenario is determined by combining the neutralino and chargino searches. These results imply a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 24.9 GeV/c ² for tanß >- 1. The search has also been extended to the case where the lightest neutralino is unstable and decays into a photon and a gravitino. imply a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 24.9 GeV/c ² for tanß >- 1. The search has also been extended to the case where the lightest neutralino is unstable and decays into a photon and a gravitino.