Search for new heavy quarks in e+e- collisions up to 46.78 GeV CM energy

H. J. Behrend*, J. Büger, L. Criegee, H. Fenner, G. Franke, J. Meyer, V. Schröder, H. Sindt, U. Timm, G. G. Winter, W. Zimmermann, P. J. Bussey, A. Campbell, J. B. Dainton, D. Hendry, J. M. Scarr, I. O. Skillicorn, K. M. Smith, M. Poppe, H. SpitzerO. Achterberg, G. D'Agostini, W. D. Apel, J. Engler, G. Flügge, B. Forstbauer, D. C. Fries, W. Fues, K. Gamerdinger, Th Henkes, G. Hopp, J. Knapp, M. Krüger, H. Küster, H. Müller, H. Randoll, K. H. Ranitzsch, G. Schmidt, H. Schneider, W. de Boer, G. Buschhorn, G. Grindhammer, P. Grosse-Wiesmann, B. Gunderson, C. Kiesling, R. Rotthaus, H. Lierl, D. Lüers, H. Oberlack, P. Schacht, G. Bonneaud, P. Colas, A. Cordier, M. Davier, D. Fournier, J. F. Grivaz, J. Haissinski, V. Journé, F. Le Diberder, U. Mallik, E. Ros, J. J. Veillet, J. H. Field, R. George, M. Goldberg, O. Hamon, F. Kapusta, F. Kovacs, R. Pain, L. Poggioli, M. Rivoal, M. Gaspero, B. Stella, R. Aleksan, J. Bouchez, G. Carnesecchi, G. Cozzika, Y. Ducros, A. Gaidot, P. Jarry, Y. Lavagne, F. Ould Saada, J. Pamela, J. P. Pansart, F. Pierre, G. Alexander, G. Bella, Y. Gnat, J. Grunhaus

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The total e+e- annihilation onto hadron has been measured at CM energies between 33.00 and 36.72 GeV and between 38.66 and 46.78 GeV in steps of 20 and 30 MeV respectively. The average of the ratio R=σ(e+e-→hadrons)/ σ is 〈R〉=3.85±0.12 and 〈R〉=4.04±0.10 for the two energy ranges. The systematic error on 〈R〉 is 0.31. Both values are consistent with the expectation for the known coloured quarks u, d, s, c and b. No evidence was found for the production of new quarks. If the largest fluctuation in R is interpreted as a narrow resonance, it corresponds to a product of the electronic width and the hadronic branching ratio ΓeeBhad>2.9 keV at the 95% confidence level, well below the value expected for the toponium vector ground state with charge 2 3e. The observed number of aplanar final states rules out the continuum production of a a new heavy flavour with pointlike cross section up to a CM energy of 45.4 GeV for a quarck charge of 1 3e. and up to 46.6 GeV for 2 3e at the 95% confidence level.

Original languageEnglish
Pages (from-to)297-301
Number of pages5
JournalPhysics Letters B
Issue number3-4
StatePublished - 30 Aug 1984


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