Measurement of cross sections and leptonic forward-backward asymmetries at theZ pole and determination of electroweak parameters

Zeitschrift für Physik C Particles and Fields - Tập 62 - Trang 551-573 - 1994
M. Acciarri1, A. Adam2, O. Adriani3, M. Aguilar-Benitez4, S. Ahlen5, J. Alcaraz6, A. Aloisio7, G. Alverson8, M. G. Alviggi7, G. Ambrosi9, Q. An10, H. Anderhub11, A. L. Anderson12, V. P. Andreev13, T. Angelescu14, L. Antonov15, D. Antreasyan16, G. Alkhazov13, P. Arce4, A. Arefiev17, T. Azemoon18, T. Aziz19, P. V. K. S. Baba10, P. Bagnaia20, J. A. Bakken21, L. Baksay22, R. C. Ball18, S. Banerjee19, K. Banicz2, J. Bao23, R. Barillère6, L. Barone20, A. Baschirotto1, R. Battiston9, A. Bay24, F. Becattini3, U. Becker12, F. Behner11, Gy. L. Bencze25, J. Berdugo4, P. Berges12, B. Bertucci9, B. L. Betev15,11, M. Biasini9, A. Biland11, G. M. Bilei9, R. Bizzarri20, J. J. Blaising26, G. J. Bobbink6,27, R. Bock28, A. Böhm28, B. Borgia20, D. Bourilkov11, M. Bourquin24, D. Boutigny6, B. Bouwens27, E. Brambilla7, J. G. Branson29, V. Brigljevic11, I. C. Brock30, M. Brooks31, A. Bujak2, J. D. Burger12, W. J. Burger24, C. Burgos4, J. Busenitz22, A. Buytenhuijs32, A. Bykov13, X. D. Cai10, M. Capell12, M. Caria9, G. Carlino7, A. M. Cartacci3, J. Casaus4, R. Castello1, N. Cavallo7, M. Cerrada4, F. Cesaroni20, M. Chamizo4, Y. H. Chang33, U. K. Chaturvedi10, M. Chemarin34, A. Chen33, C. Chen35, G. Chen35,11, G. M. Chen35, H. F. Chen36, H. S. Chen35, M. Chen12, G. Chiefari7, C. Y. Chien23, M. T. Choi37, S. Chung12, C. Civinini3, I. Clare12, R. Clare12, T. E. Coan31, H. O. Cohn38, G. Coignet26, N. Colino6, A. Contin16, S. Costantini20, F. Cotorobai14, B. de la Cruz4, X. T. Cui10, X. Y. Cui10, T. S. Dai12, R. D'Alessandro3, R. de Asmundis7, A. Degré26, K. Deiters39, E. Dénes25, P. Denes21, F. DeNotaristefani20, D. DiBitonto22, M. Diemoz20, H. R. Dimitrov15, C. Dionisi20, M. Dittmar11, L. Djambazov11, M. T. Dova10, E. Drago7, D. Duchesneau24, P. Duinker27, I. Duran40, S. Easo9, H. El Mamouni34, A. Engler30, F. J. Eppling12, F. C. Erné27, P. Extermann24, R. Fabbretti39, M. Fabre39, S. Falciano20, S. J. Fan41, A. Favara3, J. Fay34, M. Felcini11, T. Ferguson30, D. Fernandez4, G. Fernandez4, F. Ferroni20, H. Fesefeldt28, E. Fiandrini9, J. H. Field24, F. Filthaut32, P. H. Fisher23, G. Forconi12, L. Fredj24, K. Freudenreich11, W. Friebel42, M. Fukushima12, M. Gailloud43, Yu. Galaktionov17,12, E. Gallo3, S. N. Ganguli19, P. Garcia-Abia4, S. Gentile20, N. Gheordanescu14, S. Giagu20, S. Goldfarb43, Z. F. Gong36, E. Gonzalez4, A. Gougas23, D. Goujon24, G. Gratta44, M. W. Gruenewald6, C. Gu10, M. Guanziroli10, J. K. Guo41, V. K. Gupta21, A. Gurtu19, H. R. Gustafson18, L. J. Gutay2, K. Hangarter28, A. Hasan10, D. Hauschildt27, C. F. He41, J. T. He35, T. Hebbeker6, M. Hebert29, A. Hervé6, K. Hilgers28, H. Hofer11, H. Hoorani24, S. R. Hou33, G. Hu10, G. Q. Hu41, B. Ille34, M. M. Ilyas10, V. Innocente6, H. Janssen26, B. N. Jin35, L. W. Jones18, I. Josa-Mutuberria6, A. Kasser43, R. A. Khan10, Yu. Kamyshkov38, P. Kapinos42, J. S. Kapustinsky31, Y. Karyotakis6, M. Kaur10, S. Khokhar10, M. N. Kienzle-Focacci24, J. K. Kim37, S. C. Kim37, Y. G. Kim37, W. W. Kinnison31, A. Kirkby44, D. Kirkby44, S. Kirsch45, W. Kittel32, A. Klimentov12,17, A. C. König32, E. Koffeman27, O. Kornadt28, V. Koutsenko12,17, A. Koulbardis13, R. W. Kraemer30, T. Kramer12, V. R. Krastev15,9, W. Krenz28, H. Kuijten32, K. S. Kumar46, A. Kunin12,17, P. Ladron de Guevara4, G. Landi3, D. Lanske28, S. Lanzano7, A. Lebedev12, P. Lebrun34, P. Lecomte11, P. Lecoq6, P. Le Coultre11, D. M. Lee31, J. S. Lee37, K. Y. Lee37, I. Leedom8, C. Leggett18, J. M. Le Goff6, R. Leiste45, M. Lenti3, E. Leonardi20, P. Levtchenko13, C. Li36,10, H. T. Li35, P. J. Li41, J. Y. Liao41, W. T. Lin33, Z. Y. Lin36, F. L. Linde27, B. Lindemann28, L. Lista7, Y. Liu10, W. Lohmann45, E. Longo20, W. Lu44, Y. S. Lu35, J. M. Lubbers6, K. Lübelsmeyer28, C. Luci20, D. Luckey16,12, L. Ludovici20, L. Luminari20, W. Lustermann39, J. M. Ma35, W. G. Ma36, M. MacDermott11, L. Malgeri20, R. Malik10, A. Malinin17, C. Maña4, M. Maolinbay11, P. Marchesini11, F. Marion26, A. Marin5, J. P. Martin34, F. Marzano20, G. G. G. Massaro27, K. Mazumdar19, P. McBride46, T. McMahon2, D. McNally29, M. Merk30, L. Merola7, M. Meschini3, W. J. Metzger32, Y. Mi43, A. Mihul14, G. B. Mills31, Y. Mir10, G. Mirabelli20, J. Mnich28, M. Möller28, B. Monteleoni3, R. Morand26, S. Morganti20, N. E. Moulai10, R. Mount44, S. Müller28, E. Nagy25, M. Napolitano7, F. Nessi-Tedaldi11, H. Newman44, M. A. Niaz10, A. Nippe28, H. Nowak45, G. Organtini20, D. Pandoulas28, S. Paoletti20, P. Paolucci7, G. Pascale20, G. Passaleva3,9, S. Patricelli7, T. Paul23, M. Pauluzzi9, C. Paus28, F. Pauss11, Y. J. Pei28, S. Pensotti1, D. Perret-Gallix26, J. Perrier24, A. Pevsner23, D. Piccolo7, M. Pieri6, J. C. Pinto30, P. A. Piroué21, F. Plasil38, V. Plyaskin17, M. Pohl11, V. Pojidaev17,3, H. Postema12, Z. D. Qi41, J. M. Qian18, K. N. Qureshi10, R. Raghavan19, G. Rahal-Callot11, P. G. Rancoita1, M. Rattaggi1, G. Raven27, P. Razis47, K. Read38, M. Redaelli1, D. Ren11, Z. Ren10, M. Rescigno20, S. Reucroft8, A. Ricker28, S. Riemann45, B. C. Riemers2, K. Riles18, O. Rind18, H. A. Rizvi10, S. Ro37, A. Robohm11, F. J. Rodriguez4, B. P. Roe18, M. Röhner28, S. Röhner28, L. Romero4, S. Rosier-Lees26, R. Rosmalen32, Ph. Rosselet43, W. van Rossum27, S. Roth28, A. Rubbia12, J. A. Rubio6, H. Rykaczewski11, M. Sachwitz45, J. Salicio6, J. M. Salicio4, E. Sanchez4, G. S. Sanders31, A. Santocchia9, M. S. Sarakinos12, G. Sartorelli16,10, M. Sassowsky28, G. Sauvage26, C. Schäfer28, V. Schegelsky13, D. Schmitz28, P. Schmitz28, M. Schneegans26, N. Scholz11, H. Schopper48, D. J. Schotanus32, S. Shotkin12, H. J. Schreiber45, J. Shukla30, R. Schulte28, K. Schultze28, J. Schwenke28, G. Schwering28, C. Sciacca7, I. Scott46, R. Sehgal10, P. G. Seiler39, J. C. Sens6,27, L. Servoli9, I. Sheer29, D. Z. Shen41, S. Shevchenko44, X. R. Shi44, E. Shumilov17, V. Shoutko17, D. Son37, A. Sopczak6, V. Soulimov7, C. Spartiotis49, T. Spickermann28, P. Spillantini3, R. Starosta28, M. Steuer16,12, D. P. Stickland21, F. Sticozzi12, H. Stone21, K. Strauch46, K. Sudhakar19, G. Sultanov10, L. Z. Sun36,10, G. F. Susinno24, H. Suter11, J. D. Swain10, A. A. Syed32, X. W. Tang35, L. Taylor8, S. C. C. Ting12, S. M. Ting12, O. Toker9, M. Tonutti28, S. C. Tonwar19, J. Tóth25, A. Tsaregorodtsev13, G. Tsipolitis30, C. Tully21, K. L. Tung35, T. Tuuva49, J. Ulbricht11, L. Urbán25, U. Uwer28, E. Valente20, R. T. Van de Walle32, I. Vetlitsky17, G. Viertel11, P. Vikas10, U. Vikas10, M. Vivargent26, H. Vogel30, H. Vogt45, I. Vorobiev46,17, A. A. Vorobyov13, An. A. Vorobyov13, L. Vuilleumier43, M. Wadhwa26, W. Wallraff28, J. C. Wang12, C. R. Wang36, X. L. Wang36, Y. F. Wang12, Z. M. Wang10,36, A. Weber28, J. Weber11, R. Weill43, J. Wenninger24, M. White12, C. Willmott4, F. Wittgenstein6, D. Wright21, S. X. Wu10, S. Wynhoff28, B. Wyslouch12, Y. Y. Xie41, J. G. Xu35, Z. Z. Xu36, Z. L. Xue41, D. S. Yan41, B. Z. Yang36, C. G. Yang35, G. Yang10, C. H. Ye10, J. B. Ye36, Q. Ye10, S. C. Yeh33, Z. W. Yin41, J. M. You10, N. Yunus10, M. Yzerman27, C. Zaccardelli44, P. Zemp11, M. Zeng10, Y. Zeng28, D. H. Zhang27, Z. P. Zhang36,10, B. Zhou5, G. J. Zhou35, J. F. Zhou28, R. Y. Zhu44, A. Zichichi16,6,10, B. C. C. van der Zwaan27
1INFN Sezione di Milano, Milan, Italy
2Purdue University, West Lafayette, USA
3INFN Sezione di Firenze and University of Florence, Florence, Italy
4Certro de Investigaciones Energeticas, Medioambientales y Technologicas, CIEMAT, Madrid, Spain
5Boston University, Boston, USA
6European Laboratory for Particle Physics (CERN), Geneva 23, Switzerland
7INFN-Sezione di Napoli and University of Naples, Naples, Italy
8Northeastern University, Boston, USA
9INFN-Sezione di Perugia and Universitá Degli Studi di Perugia, Perugia, Italy
10FBLJA Project, World Laboratory, Geneva 23, Switzerland
11Eiogenössische Technische Hochschule, ETH Zürich, Zürich, Switzerland
12Massachusetts Institute of Technology, Cambridge, USA
13Nuclear Physics Institute, St. Petersburg, Russia
14Institute of Atomic Physics and University of Bucharest, Bucharest, Romania
15Institute of Mechantronics, Bulgarian Academy of Sciences, Sona, Bulgaria
16INFN Sezione di Bologna, Bologna, Italy
17Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia
18University of Michigan, Ann Arbor, USA
19Tata Institute of Fundamental Research, Bombay, India
20INFN-Sezione di Roma and University of Rome, Rome, Italy
21Princeton University, Princeton, USA
22University of Alabama, Tuscaloosa, USA
23Johns Hopkins University, Baltimore, USA
24University of Geneva, Geneva 4, Switzerland
25Central Research Institute for Physics of the Hungarian Academy of Sciences, Budapest 114, Hungary
26Laboratoire d’Annecy-le-Vieux de Physique des Particules, LAPP, IN2P3-CNRS, Annecy-le-Vieux CEDEX, France
27NIKHEF, National Institute for High Energy Physics, Amsterdam, The Netherlands
28I. Physikalisches Institut, III. Physikalisches Institut, RWTH, Aachen, Germany
29University of California, San Diego, USA
30Carnegie Mellon University, Pittsburgh, USA
31Los Alamos National Laboratory, Los Alamos, USA
32University of Nijmegen and NIKHEF, Nijmegen, The Netherlands
33High Energy Physics Group, Tarwan, China
34Institut de Physique Nucléaire de Lyon, IN2P3-CNRS, Université Claude Bernard, Villeurbanne Cedex, France
35Institute of High Energy Physics, IHEP, Berjing, People's Republic of China
36USTC, Chinese University of Science and Technology, Hefei, Anhui, People's Republic of China
37Center for High Energy Physics, Korea Advanced Inst. of Sciences and Technology, Taejon, Republic of Korea
38Oak Ridge National, Laboratory, Oak Ridge, USA
39Paul Scherrer Institut PSI, Villigen, Switzerland
40Dept. de Fisica de Particulas Elementales, Univ. de Santiago, Santiago de Compostela, Spain
41Shanghai Institute of Ceramics, SIC, Shanghai, China
42DESY-Institut für Hochenergiephysik, Zeuthen, Germany
43University of Lausanne, Lausanne, Switzerland
44California Institute of Technology, Pasadena, USA
45DESY, Institut für Hochenergiephysik, Zeuthen, Germany
46Harvard University, Cambridge, USA
47Department of Natural Sciences, University of Cyprus, Nicosia, Cyprus
48University of Hamburg, Hamburg, Germany
49Research Institute for High Energy Physics, SEFT, Helsinki, Finland

Tóm tắt

We report on the measurement of the leptonic and hadronic cross sections and leptonic forward-backward asymmetries at theZ peak with the L3 detector at LEP. The total luminosity of 40.8 pb−1 collected in the years 1990, 1991 and 1992 corresponds to 1.09·106 hadronic and 0.98·105 leptonicZ decays observed. These data allow us to determine the electroweak parameters. From the cross sections we derive the properties of theZ boson: $$\begin{gathered} M_Z = 91195 \pm 9MeV\Gamma _{\rm Z} = 2494 \pm 10MeV \hfill \\ \Gamma _{had} = 1748 \pm 10MeV\Gamma _\ell = 83.49 \pm 0.46MeV \hfill \\ \end{gathered} $$ assuming lepton universality. We obtain an invisible width of Γinv=496.5±7.9 MeV which, in the Standard Model, corresponds to a number of light neutrino species ofN v=2.981±0.050. Using also the three leptonic forward-backward asymmetries and the average tau polarization, we determine the effective vector and axial-vector coupling constants of the neutral weak current to charged leptons to be: $$\bar g^\ell v = - 0.0378_{ - 0.0042}^{ + 0.0045} \bar g^\ell _A = - 0.4998 \pm 0.0014.$$ Within the framework of the Standard Model, and including our measurements of the $$Z \to b\bar b$$ forward-backward asymmetry and partial decay width, we derive an effective electroweak mixing angle of $$sin^2 \bar \theta _W = 0.2326 \pm 0.0012$$ . We obtain an estimate for the strong coupling constant, αS=0.142 ± 0.013 and for the top-quark mass,m t =158 −40 +32 ±19(Higgs) GeV, where the second error arises due to the uncertainty in the Higgs-boson mass.

Tài liệu tham khảo

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Zeitschrift für Physik C Particles and Fields

Tập 62

551-573

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