A Search for Scalar Leptoquarks in Z 0 Decays The OPAL Collaboration

A search for scalar leptoquarks has been performed with data from the OPAL detector at the e+estorage ring LEP. In a data sample corresponding to an integrated luminosity of 6.3pb-1 no evidence for leptoquark production was observed where the leptoquark decays into a quark and either a charged lepton ( e, p., r) or a neutrino. An upper limit of 1. 7 pb on the production cross section for leptoquarks is obtained assuming a branching ratio of 50% for the decay of the leptoquark into the channels with a charged lepton. Lower limits on the leptoquark mass between 41.4 and 46.4GeVjc2 at 95% CLare obtained, depending on the effective SU(2) X U(1) invariant couplings assigned to the leptoquark. (Submitted to Physics Letters B) The OPAL Collaboration G.Alexander23 , J.Allison1s, P.P.Allport5 , K.J.Anderson9 , S.Arcelli2 , J.C.Armitages, P.Ashton1s, A.Astbury•, D.Axenb, G.Azuelos18•c, G.A.Bahan1s, J.T.M.Baines1s, A.H.Ball17, J.Banks1s, G.J. Barker13 , R.J. Barlow1s, J.R. Batley5 , G. Beaudoin18 , A. Beck23 , J. Becker10 , T. Behnke8 , K.W. Bell20 , G. Bella23 , S. Bethke11 , 0. Biebel3 , U. Binder10 , I.J. Bloodworth', P. Bock11 , H.M. Bosch11 , S. Bougerolleb, B.B. Brabson12 , H. Breuker8 , R.M.Brown20 , R.Brun8 , A. Buijs8 , H.J.Burckhart8 , P.Capiluppi2 , R.K.Carnegies, A.A.Carter13 , J.R.Carter5 , C.Y.Chang17 , D.G. Charlton8 , J.T.M. Chrin1s, P.E.L. Clarke25 , I. Cohen23 , W.J. Collins5 , J.E. Conboy15 , M. Cooper22 , M. Couch1 , M. Coupland14 , M. Cuffiani2 , S.Dado , G.M.Dallavalle2 , S. De Jong8 , P.Debu21 , M.M.Deninno2 , A.Dieckmann11 , M.Dittmar\ M.S.Dixit7 , E.Duchovni26 , G.Duckeck11 , I.P.Duerdoth16 , D.J.P.Dumas6 , G.Ecker!in11 , P.A.Elcombe5 , P.G.Estabrooks6 , E.Etzion23 , F. Fabbri2 , M. Fincke-Keeler•, H.M. Fischer3 , D.G. Fong17, C. Fukunaga24, A. Gaidot 2', 0. Ganel2s, J.W. Gary11 , J. Gascon18 , R.F.McGowan16 , N.I. Geddes20 , C. Geich-Gimbel3 , S.W. Gensler9 , F.X. Gentit 2', G. Giacomelli2 , V. Gibson5 , W.R. Gibson13 , J.D. Gillies20 , J. Goldberg22 , M.J. Goodrick5 , W. Gorn4, C. Grandi2 , E. Gross26 , J. Hagemann8 , G.G.Hanson12 , M.Hansrou!8 , C.K. Hargrove7 , P.F. Harrison13, J. Hart 5 , P.M. Hattersley', M. Hauschild8 , C.M. Hawkes8 , E. Heflin\ R.J. Hemingways, R.D. Heuer8 , J. C. Hi115 , S.J. Hillier', D .A. Hinshaw18 , C. Ho\ J.D. Hobbs9 , P.R.Hobson25 , D.Hochman26 , B.Holl8 , R.J.Homer', S.R.Hou17 , C.P.Howarth1S, R.E. Hughes-Jones16 , R. Humbert10 , P.Igo-Kemenes11 , H.Ihssen11 , D.C. Imrie25 , L. Janissens, A.Jawahery17 , P.W.Jeffreys20 , H.Jeremie18 , M.Jimack2 , M.Jobes1 , R.W.L.Jones13 , P.Jovanovic1 , D. Karlens, K. Kawagoe2\ T. Kawamoto2\ R.K. Keeler•, R.G. Kellogg17, B.W. Kennedy15 , C.Kleinwort8 , D.E.Klem19 , T.Kobayashi24 , T.P.Kokott3 , S.Komarniya24 , L.Kiipkes, R. Kowa!ewski6 , H. Kreutzmann3 , J. von Krogh11 , J. Kroll , M. Kuwano24, P. Kyberd13 , G.D.Lafferty16 , F.Lamarche1s, W.J.Larson4 , J.G.Layter\ P.Le Du21 , P.Leblanc1s, A.M.Lee17 , M.H.Lehto15 , D.Lellouchs, P.Lennert11 , C.Leroy1s, L.Lessard1s, S.Levegriin3 , L.Levinson2s, S.L.Lloyd13 , F.K.Loebinger1s, J.M.Lorah17, B.Lorazo1s, M.J.Losty7 , X.C.Lou12 , J.Ludwig10 , M.Mannellis, S.Marcellini2 , G.Maringer3 , A.J.Martin13, J.P.Martin1s, T.Mashimo24, P.Miittig3 , U.Maur3 , T.J.McMahon1 , J.R.McNutt25 , F.Meijerss, D.Menszner11 , F.S.Merritt9 , H.Mes7 , A. Miche!ini8 , R.P. Middleton20 , G. Mikenberg26 , J. Mildenbergers, D.J. Miller15 , C. Mi!stene23 , R.Mir12 , W.Mohr10 , C.Moisan1s, A.Montanari2 , T.Mori24 , M.W.Moss16 , T.Mouthuy12 , P.G.Murphy16 , B.Nellen3 , H.H.Nguyen9 , M.Nozaki24 , S.W.O'Nea!es,d, B.P.O'Neill\ F.G. Oakham7 , F. Odorici2 , M. Oggs, H.O. Ogren12 , H. Oh\ C.J. Oram•, M.J. Oreg!ia , S. Orito2\ J.P. Pansart 21 , B. Panzer-Steindels, P. Paschievici26 , G.N. Patrick20, S.J. Pawley1s, P. Pfister10 , J.E. Pilcher9 , J.L. Pinfold26 , D.E.Plane8 , P. Poffenberger", B. Po!i2 , A. Pouladdejs, E. Prebyss, T.W. Pritchard13 , H. Przysiezniak1s, G. Quasts, M.W.Redmond9 , D.L. Rees', K. Riles\ S.A.Robins13, D.Robinsons, A.Rollnik3 , J.M.Roney9 , S.Rossberg10 , A.M.Rossi2.!, P.Routenburg6 , K. Runge10 , 0. Runo!fssons, D.R. Rust12 , S. Sangheras, M. Sasaki24, A.D. Schaile10 , 0. Schaile10 , W. Schapperts, P. Scharff-Hansens, P. Schenk", H. von der Schmitt11 , S. Schreiber3 , J. Schwarz10 , W.G.Scott 20 , M.Settles12 , B.C.Shen\ P.Sherwood15 , R.Shypitb, A.Simon3 , P.Singh13 , G.P.Siroli2 , A. Skuja17 , A.M. Smiths, T.J. Smiths, G.A. Snow17 , R. Sobie", R.W.Springer17 , M. Sproston20 , K. Stephens's, H.E. Stier10 , D. Strom9 , H. Takeda24 , T. Takeshita24 , P. Taras1s, S. Tarem26 , P. Teixeira-Diaz11 , N.J. Thackray', T. Tsukamoto2\ M.F. Turner5 , G. Tysarczyk-Niemeyer11 , D. Van den plas1s, R. Van Kootens, G.J. VanDalen\ G. Vasseur21 , C.J. Virtue19 , A. Wagner11 , C. Wa!U10 , J.P. Walker1 , C.P. Ward5 , D.R. Ward5 , P.M. Watkins1 , A.T. Watson', N.K. Watsons, M. Weber11 , S. Weiszs, P.S. Wells8 , N. Wermes11 , M. Weymanns, M.A. Whalley1 , G.W. Wi!son21 , J.A. Wilson', I. Wingerters, V-H. Winterer10, N.C. Wood1s, S. Wottons, T.R. Wyatt1s, R. Yaari2s, Y. Yang4 •h, G. Yekutie!i26 , I. Zacharovs, W. Zeuners, G.T. Zorn17.