Searches for scalar top and scalar bottom quarks at LEP2

R Barate,O Buchmüller,J Steinberger,G.A Blair,M Corden,R Xu,N Konstantinidis,M Delfino,P Azzurri,C Vannini,A Tilquin,J Walsh,E Locci,A Pacheco,G Iaselli,K Kleinknecht,E Focardi,S Chen,B Rensch,W Cameron,L Bosisio,R.W Williams,G Sanguinetti,A Rougé,F Palla,G Lutters,C Grupen,S Goodsir,L Silvestris,L Moneta,M.-N Minard,E Lançon,A Cordier,M Jacquet,P Morawitz,G Calderini,S Bettarini,C Boyer,G Rizzo,A Putzer,H Seywerd,J.J Aubert,F Machefert,T Sloan,K Jakobs,M De Palma,R Alemany,H Videau,R Berlich,P Coyle,P Tempesta,S.R Armstrong,M Lehto,A Böhrer,I Lehraus,M Davier,T.R Edgecock,C Bozzi,F Motsch,C Hoffmann,H Wachsmuth,M Apollonio,M Schmitt,G Lütjens,S Dhamotharan,S Jin,P Comas,T Medcalf,R Cavanaugh,P Maley,R.M Turnbull,L.F Thompson,G Gelao,B Vallage,Q Ouyang,M Maggi,G Hughes,W Wiedenmann,S González,V Chiarella,A Bonissent,I Videau,M Rumpf,S.N Black,A Blondel,C Geweniger,J Reeve,G Graefe,O Callot,J Carr,A Venturi,V Büscher,R Della Marina,C Markou,S Monteil,P Laurelli,G Selvaggi,J.-F Grivaz,D Buskulic,J.M Crespo,A Vayaki,W Kozanecki,J Boucrot,M Cattaneo,A Rosowsky,B Jost,P Payre,A Giassi,G Merino,K Trabelsi,A Falvard,K Affholderbach,G Crawford,G Bencivenni,G Hansper,F Ranjard,G Rudolph,S Wasserbaech,P.A Mcnamara,T Huehn,R Settles,A.E Wright,A Höcker,P Rosnet,D Schlatter,A Ealet,B Pietrzyk,L Duflot,E Tournefier,G Bologna,R Richter,G Zito,P Spagnolo,A Minten,A Moutoussi,U Becker,Z Ajaltouni,W Tejessy,J.C Thompson,J Proriol,C.N Booth,P Girtler,C Goy,F Combley,A Ranieri,E Charles,F Ligabue,P Campana,Ll Garrido,M.A Mcneil,J Rothberg,B Fabbro,M Chmeissani,I Ferrante,M.S Kelly,X Wu,W Orejudos,W Blum,G Ganis,K Zachariadou,G Wolf,D Casper,P Janot,A Lucotte,F Thomson,A Lusiani,J Zhang,I Riu,S Xue,P Perrodo,H Stenzel,F Murtas,D.P.S Ferguson,C Raine,F Bossi,J.G Lynch,M Aleppo,A Trabelsi,M Frank,M Wunsch,J.H Dann,E Thomson,G Parrini,C Benchouk,B Michel,P Colas,A Sciabà,H Hu,V Hepp,D Rousseau,J Harvey,B Bloch-Devaux,D Abbaneo,G Dissertori,F Stephan,H Kroha,A Roussarie,G Mannocchi,S Simion,A.W Halley,O.J Hayes,D Fouchez,M.I Williams,J Schwindling,J Lin,C Guicheney,G Capon,D Pallin,J Sommer,E Simopoulou,J Knobloch,T Fearnley,F Cerutti,G Bagliesi,D Creanza,J.T Chambers,J Lefrançois,C Diaconu,G Daskalakis,H Dietl,P Hanke,W Zhao,G Raso,A Wäänänen,W Männer,L Curtis,P Colrain,M Antonelli,A Messineo,M Pepe-Altarelli,T Wang,O Leroy,G Felici,Y Xie,L Passalacqua,H Drevermann,P Bright-Thomas,F Foster,F Teubert,M Girone,A Wagner,A Colaleo,E Rohne,G Zobernig,A Gregorio,C Zeitnitz,A.O Bazarko,A Sadouki,V Ciulli,P Henrard,C Gotzhein,G Cowan,S Nuzzo,R Miquel,F Ruggieri,T.C Greening,B.S Nilsson,P Elmer,E Kneringer,J Nielsen,A Rosado-Schlosser,L Zhang,J Nash,C Ferdi,J Rander,A Antonelli,F Le Diberder,B Gobbo,G Bujosa,N Marinelli,A Tricomi,J Jousset,R Beuselinck,G Quast,R Fantechi,A Kyriakis,G Sguazzoni,S Werner,R Hagelberg,P Van Gemmeren,D Zerwas,M Thulasidas,P Teixeira-Dias,P Perret,B Renk,G Giannini,S Schael,G Musolino,Y Saadi,F Podlyski,L Serin,A Valassi,F Ragusa,C Georgiopoulos,K Tittel,M Talby,O Schneider,M P Casado ,M Williams ,A S Thompson ,D W Kim ,Pedro Saraiva ,D Botterill ,Y S Gao ,J M Nachtman ,J M Yamartino ,J F Foss ,J A Strong ,M G Green ,R W L Jones ,E B Martin ,R Forty ,M H Schune ,R St Denis ,K M Smith ,Ph Ghez ,M Fernández-Bosman ,C Brew ,M C Lemaire ,P H Hansen ,Р Тенчини ,D M Binnie ,A M Litke ,J P Schuller ,S J Haywood ,E P Whelan ,J A Perlas ,I R Tomalin ,G N Taylor ,P Heusse ,L M Mir ,C Padilla Aranda ,J J Veillet ,E.-E Kluge ,Á Pascual ,G Lütz ,J C Brient ,A Juste Rozas ,J M Scarr ,M Martı́nez ,J R Hansen ,P R Norton ,J D Hansen ,P J Dornan ,J F Renardy ,I G Knowles ,J M Rossignol ,D E Jaffe ,A M Lutz ,J C Montret ,D Décamp ,J P Lees ,S L Cartwright ,J F Pusztaszeri ,S L Wu ,W M Newton ,H G Sander ,H Y Kim ,Y Pan ,Siegmund Brandt ,S J Dorris ,A M Stacey ,A P Betteridge ,R W Clifft ,J.y Nief ,F J Munoz Sanchez ,P S Marrocchesi ,V O’shea ,J Pütz ,J K Sedgbeer ,J H Von Wimmersperg-Toeller ,G Rolandi ,P G Verdini ,P Pérez ,E Fernández ,I Scott ,Irena Nikolić ,L Smolík ,D Kühn ,A Barrès ,Rod Boswell ,A J Finch ,P Mató ,V M Ghete ,L M Bryant ,X T Huang ,I C Park ,R Dell’orso ,J B Hansen ,H G Moser ,A Jachołkowska ,C K Bowdery ,G Mäggi

doi:10.1016/s0370-2693(97)01178-7

Abstract

Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb^-1 taken at sqrt{s} = 161, 170, and 172~GeV and 5.7 pb^-1 taken at sqrt{s} = 130 and 136~GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels stop --> c chi, stop --> b l snu, and sbottom --> b chi. For the channel stop --> c chi a limit of 67 GeV/c^2 has been set on the scalar top quark mass, independent of the mixing angle between the supersymmetric partners of the left and right-handed states of the top quark. This limit assumes a mass difference between the stop and the chi of at least 10 GeV/c^2. For the channel stop --> b l snu the mixing-angle independent scalar top limit is 70 GeV/c^2, assuming a mass difference between the stop and the snu of at least 10 GeV/c^2. For the channel sbottom --> b chi, a limit of 73 GeV/c^2 has been set on the mass of the supersymmetric partner of the left-handed state of the bottom quark. This limit is valid if the mass difference between the sbottom and the chi is at least 10 GeV/c^2.

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