PARTICLES AND FIELDS THIRD SERIES, VOLUME 34, NUMBER 3 1 AUGUST 1986 Study of hadron and inclusive muon production from e+e annihilation at 39. 79&~s &46. 78 Gev B. Adeva, S. Ansari, U. Becker, ' R. Becker-Szendy, ' J. Berdugo, A. Boehm, ' J. G. Branson, ' J. D. Burger, ' M. Capell, ' M. Cerrada, C. C. Chang, ' Y. H. Chang, ' H. S. Chen, ' M. Chen, " M. L. Chen, ' M. Y. Chen, ' Y. K. Chi, ' E. Deffur, ' K. Deiters, ' M. Demarteau, s M. Dhina, ' B. Z. Dong, ' P. Duinker, s H. S. Fesefeldt, ' D. Fong, ' M. Fukushima, ' L. Garrido, R. D. Han, ' D. Harting, g G. Herten, ' M. C. Ho, ' D. Hueser, ' M. Hussain, M. M. Ilyas, ' D. Z. Jiang, ' M. Klein, ' %. Krenz, ' P. Kuijer, g R. Leiste, ' Q. Z. Li, " D. Linnhoefer, ' D. Luckey, ' E. J. Luit, s H. Ma, ' C. Mana, M. A. Marquina, M. Martinez, G. G. G. Massaro, s J. Mnich, ' K. Nadeem, H. Newman, '%. D. Nowak, " M. Nusbaumer, " M. Pohl, " F. P. Poschmann, R. R. Rau, S. Rodriguez, M. Rohde, " J. A. Rubio, H. Rykaczewski, ' M. Sachwitz, ' J. Salicio, H. J. Schreiber, ' U. Schroeder, ' J. Schug, ' H. Stone, ' G. M. Swider, H. %. Tang, ' D. Teuchert, ' Samuel C. C. Ting, ' K. L. Tung, ' H. Vogt, " M. Q. Wang, ' M. White, ' H. G. Wu, ' S. X. %u, ' M. F. %'yne, B. %'yslouch, ' B. X. Yang, ' X. Yu, ' L. S. Zhang, ' Z. H. Zhang, ' B. Zhou, ' and R. Y. Zhu' IIL Physikali. sches Institut, Technische Hochschule, D 5IOO Aach-en, Federal Republic of Germany Brookhaven Xational Laboratory, Upton, Yew York 11973 California Institute of Technology, Pasadena, California 9II25 dDeutsches Elektronen Synchrotron, Notkestrasse 85, D 2000 Hambu-rg 52, Federal Republic of Germany 'Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Junta de Energy'a iVuclear, Madrid, Spain sNationaal Instituut voor Kernfysica en Hoge Energiefysica -(NIKHEF), 1009 DI3, Amster-dam, The Netherlands "Universite de Geneve, 1211 Geneve 4, Switzerland 'Institute of High Energy Physics, Chinese Academy of Science, Peking, People's Republic of China Institut fiir Hochenergiephysik, Akademie der Wissenschaften der Deutschen Demokratischen Republik, )615 Berlin-Zeuthen, Deutschen Demokratischen Republik Eidgenossisch-Technische Hochschule Zurich, CH 8093 Zurich, Switzerland (Received 27 January 1986j %e use the reaction e+e ~hadrons, in. the Mark J detector at the DESY electron-positron col- lider PETRA, to determine the hadronic cross section up to 46.78 GeV. The production of a top quark with a charge equal to —, is excluded up to 46.6 GeV with 95% C.L. The observed rise in the cross section at higher energies is consistent with the electroweak prediction for a Z mass of 93 GeV. %'e describe some unusual muon inclusive events. I. INTRODUCTION PETRA, the electron-positron collider at DESY, has a maximum center-of-mass energy of 46.78 GeV. In this paper the Mark J collaboration reports results on hadron production in the highest-energy interval, 39. 79 & v s (46. 78 GeV (Ref. I). The standard electroweak model and quantum chromodynamics (QCD) are, as of now completely successful in describing the electromagnetic, weak, and strong interactions. One prediction which is not experimentally established as yet is the observation of a sixth (top) quark, with a positive electric charge equal in magnitude to — ', that of the electron. Observation of the top quark would complete the postulated third family of quarks. ' %e discuss data collection and analysis techniques in Sec. II. Section III outlines the determination of the total hadronic cross section and its use in the search for the top quark using both the cross section and event thrust distri- butions. Section IV addresses the electroweak effects. Section V focuses on some hadron events with unusual configurations and characteristics which contain at least one high-energy muon. Their origin remains unexplained. 34 681 1986 The American Physical Society