Search for scalar top and scalar bottom quarks at √s = 170-172 GeV in e+e- collisions

K. Ackerstaff, G. Alexander, J. Allison, N. Altekamp, K. J. Anderson, S. Anderson, S. Arcelli, S. Asai, D. Axen, G. Azuelos, A. H. Ball, E. Barberio, R. J. Barlow, R. Bartoldus, J. R. Batley, S. Baumann, J. Bechtluft, C. Beeston, T. Behnke, A. N. BellK. W. Bell, G. Bella, S. Bentvelsen, P. Berlich, S. Bethke, O. Biebel, A. Biguzzi, S. D. Bird, V. Blobel, I. J. Bloodworth, J. E. Bloomer, M. Bobinski, P. Bock, D. Bonacorsi, M. Boutemeur, B. T. Bouwens, S. Braibant, L. Brigliadori, R. M. Brown, H. J. Burckhart, C. Burgard, R. Bürgin, P. Capiluppi, R. K. Carnegie, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, D. Chrisman, P. E.L. Clarke, I. Cohen, J. E. Conboy, O. C. Cooke, M. Cuffiani, S. Dado, C. Dallapiccola, G. M. Dallavalle, S. De Jong, L. A. Del Pozo, K. Desch, M. S. Dixit, E. Do Couto E Silva, M. Doucet, E. Duchovni, G. Duckeck, I. P. Duerdoth, D. Eatough, J. E.G. Edwards, P. G. Estabrooks, H. G. Evans, M. Evans, F. Fabbri, M. Fanti, A. A. Faust, F. Fiedler, M. Fierro, H. M. Fischer, I. Fleck, R. Folman, D. G. Fong, M. Foucher, A. Fürtjes, D. I. Futyan, P. Gagnon, J. W. Gary, J. Gascon, S. M. Gascon-Shotkin, N. I. Geddes, C. Geich-Gimbel, T. Geralis, G. Giacomelli, P. Giacomelli, R. Giacomelli, V. Gibson, W. R. Gibson, D. M. Gingrich, D. Glenzinski, J. Goldberg, M. J. Goodrick, W. Gorn, C. Grandi, E. Gross, J. Grunhaus, M. Gruwé, C. Hajdu, G. G. Hanson, M. Hansroul, M. Hapke, C. K. Hargrove, P. A. Hart, C. Hartmann, M. Hauschild, C. M. Hawkes, R. Hawkings, R. J. Hemingway, M. Herndon, G. Herten, R. D. Heuer, M. D. Hildreth, J. C. Hill, S. J. Hillier, T. Hilse, P. R. Hobson, R. J. Homer, A. K. Honma, D. Horváth, R. Howard, D. E. Hutchcroft, P. Igo-Kemenes, D. C. Imrie, M. R. Ingram, K. Ishii, A. Jawahery, P. W. Jeffreys, H. Jeremie, M. Jimack, A. Joly, C. R. Jones, G. Jones, M. Jones, U. Jost, P. Jovanovic, T. R. Junk, D. Karlen, V. Kartvelishvili, K. Kawagoe, T. Kawamoto, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, J. Kirk, A. Klier, S. Kluth, T. Kobayashi, M. Kobel, D. S. Koetke, T. P. Kokott, M. Kolrep, S. Komamiya, T. Kress, P. Krieger, J. Von Krogh, P. Kyberd, G. D. Lafferty, R. Lahmann, W. P. Lai, D. Lanske, J. Lauber, S. R. Lautenschlager, J. G. Layter, D. Lazic, A. M. Lee, E. Lefebvre, D. Lellouch, J. Letts, L. Levinson, S. L. Lloyd, F. K. Loebinger, G. D. Long, M. J. Losty, J. Ludwig, A. Macchiolo, A. Macpherson, M. Mannelli, S. Marcellini, C. Markus, A. J. Martin, J. P. Martin, G. Martinez, T. Mashimo, P. Mättig, W. J. McDonald, J. McKenna, E. A. Mckigney, T. J. McMahon, R. A. McPherson, F. Meijers, S. Menke, F. S. Merritt, H. Mes, J. Meyer, A. Michelini, G. Mikenberg, D. J. Miller, A. Mincer, R. Mir, W. Mohr, A. Montanari, T. Mori, M. Morii, U. Müller, K. Nagai, I. Nakamura, H. A. Neal, B. Nellen, R. Nisius, S. W. O'Neale, F. G. Oakham, F. Odorici, H. O. Ogren, N. J. Oldershaw, M. J. Oreglia, S. Orito, J. Pálinkas, G. Pásztor, J. R. Pater, G. N. Patrick, J. Patt, M. J. Pearce, S. Petzold, P. Pfeifenschneider, J. E. Pilcher, J. Pinfold, D. E. Plane, P. Poffenberger, B. Poli, A. Posthaus, H. Przysiezniak, D. L. Rees, D. Rigby, S. Robertson, S. A. Robins, N. Rodning, J. M. Roney, A. Rooke, E. Ros, A. M. Rossi, M. Rosvick, P. Routenburg, Y. Rozen, K. Runge, O. Runolfsson, U. Ruppel, D. R. Rust, R. Rylko, K. Sachs, T. Saeki, E. K.G. Sarkisyan, C. Sbarra, A. D. Schaile, O. Schaile, F. Scharf, P. Scharff-Hansen, P. Schenk, J. Schieck, P. Schleper, B. Schmitt, S. Schmitt, A. Schöning, M. Schröder, H. C. Schultz-Coulon, M. Schulz, M. Schumacher, C. Schwick, W. G. Scott, T. G. Shears, B. C. Shen, C. H. Shepherd-Themistocleous, P. Sherwood, G. P. Siroli, A. Sittler, A. Skillman, A. Skuja, A. M. Smith, G. A. Snow, R. Sobie, S. Söldner-Rembold, R. W. Springer, M. Sproston, K. Stephens, J. Steuerer, B. Stockhausen, K. Stoll, D. Strom, P. Szymanski, R. Tafirout, S. D. Talbot, S. Tanaka, P. Taras, S. Tarem, R. Teuscher, M. Thiergen, M. A. Thomson, E. Von Törne, S. Towers, I. Trigger, E. Tsur, A. S. Turcot, M. F. Turner-Watson, P. Utzat, R. Van Kooten, M. Verzocchi, P. Vikas, E. H. Vokurka, H. Voss, F. Wäckerle, A. Wagner, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, N. Wermes, J. S. White, B. Wilkens, G. W. Wilson, J. A. Wilson, G. Wolf, T. R. Wyatt, S. Yamashita, G. Yekutieli, V. Zacek, D. Zer-Zion

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Abstract

A search for a scalar top quark has been performed using a total data sample of 10.4 pb-1 at centre-of-mass energies of √s = 170 and 172 GeV collected with the OPAL detector at LEP. No candidate events were observed. Combining this result with those obtained at √s = 130, 136 and 161 GeV, the 95% C.L. lower limit on the scalar top quark mass is 66.8 GeV, if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is smaller than π/4. If the mixing angle is zero, the limit is 73.3 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark in which it decays into a bottom quark, a charged lepton and a scalar neutrino was also studied. From a similar analysis, a mass limit on the light scalar bottom quark was set at 69.7 GeV, for a mixing angle between the supersymmetric partners of the left- and right-handed states of the bottom quark of zero, and the mass difference between the scalar bottom quark and the lightest neutralino larger than 8 GeV.

Original languageEnglish
Pages (from-to)409-420
Number of pages12
JournalZeitschrift fur Physik C-Particles and Fields
Volume75
Issue number3
DOIs
StatePublished - Jul 1997
Externally publishedYes

Funding

Acknowledgements. We particularly wish to thank the SL Division√ for the efficient operation of the LEP accelerator at the new energies of s = 170– 172 GeV and for their continuing close cooperation with our experimental group. We thank our colleagues from CEA, DAPNIA/SPP, CE-Saclay for their efforts over the years on the time-of-flight and trigger systems which we continue to use. In addition to the support staff at our own institutions we are pleased to acknowledge the Department of Energy, USA, National Science Foundation, USA, Particle Physics and Astronomy Research Council, UK, Natural Sciences and Engineering Research Council, Canada, Israel Science Foundation, administered by the Israel Academy of Science and Humanities, Minerva Gesellschaft, Japanese Ministry of Education, Science and Culture (the Monbusho) and a grant under the Monbusho International Science Research Program, German Israeli Bi-national Science Foundation (GIF), Bundesministerium für Bildung, Wissenschaft, Forschung und Tech-nologie, Germany, National Research Council of Canada, Hungarian Foundation for Scientific Research, OTKA T-016660, and OTKA F-015089.

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