6533b860fe1ef96bd12c309f

RESEARCH PRODUCT

Model-independent measurement of the W-boson helicity in top-quark decays at D0.

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Made available in DSpace on 2022-04-28T20:37:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-14 Science and Technology Facilities Council We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1fb-1 sample of candidate tt̄ events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp̄ Collider. We reconstruct the angle θ* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos θ* distribution finds that the fraction of longitudinal W bosons f0=0.425±0.166(stat)±0.102(syst) and the fraction of right-handed W bosons f+=0.119±0.090(stat)±0.053(syst), which is consistent at the 30% C.L. with the standard model. © 2008 The American Physical Society. Universidad de Buenos Aires, Buenos Aires LAFEX Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro Universidade Do Estado Do Rio de Janeiro, Rio de Janeiro Universidade Federal Do ABC, Santo André Instituto de Física Teórica Universidade Estadual Paulista, São Paulo University of Alberta, Edmonton, AB University of Science and Technology of China, Hefei Universidad de Los Andes, Bogotá Center for Particle Physics Charles University, Prague Czech Technical University, Prague Center for Particle Physics Institute of Physics Academy of Sciences of the Czech Republic, Prague Universidad San Francisco de Quito, Quito LPC Univ Blaise Pascal CNRS/IN2P3, Clermont LPSC Université Joseph Fourier Grenoble 1 Institut National Polytechnique de Grenoble CPPM IN2P3/CNRS Université de la Méditerranée, Marseille LAL Univ Paris-Sud IN2P3/CNRS, Orsay LPNHE IN2P3/CNRS Universités Paris VI and VII, Paris DAPNIA/Service de Physique des Particules CEA, Saclay IPHC Université Louis Pasteur CNRS/IN2P3, Strasbourg IPNL Université Lyon 1 CNRS/IN2P3, Villeurbanne III. Physikalisches Institut A RWTH Aachen, Aachen Physikalisches Institut Universität Bonn, Bonn Physikalisches Institut Universität Freiburg, Freiburg Institut für Physik Universität Mainz, Mainz Ludwig-Maximilians-Universität München, München Fachbereich Physik University of Wuppertal, Wuppertal Panjab University, Chandigarh Delhi University, Delhi Tata Institute of Fundamental Research, Mumbai University College Dublin, Dublin Korea Detector Laboratory Korea University, Seoul SungKyunKwan University, Suwon CINVESTAV, Mexico City FOM-Institute NIKHEF University of Amsterdam/NIKHEF, Amsterdam Radboud University Nijmegen/NIKHEF, Nijmegen Joint Institute for Nuclear Research, Dubna Institute for Theoretical and Experimental Physics, Moscow Moscow State University, Moscow Institute for High Energy Physics, Protvino Petersburg Nuclear Physics Institute, St. Petersburg Lund University, Lund Physik Institut Universität Zürich, Zürich Lancaster University, Lancaster Imperial College, London University of Manchester, Manchester University of Arizona, Tucson, AZ 85721 Lawrence Berkeley National Laboratory University of California, Berkeley, CA 94720 California State University, Fresno, CA 93740 University of California, Riverside, CA 92521 Florida State University, Tallahassee, FL 32306 Fermi National Accelerator Laboratory, Batavia, IL 60510 University of Illinois at Chicago, Chicago, IL 60607 Northern Illinois University, DeKalb, IL 60115 Northwestern University, Evanston, IL 60208 Indiana University, Bloomington, IN 47405 University of Notre Dame, Notre Dame, IN 46556 Purdue University Calumet, Hammond, IN 46323 Iowa State University, Ames, IA 50011 University of Kansas, Lawrence, KS 66045 Kansas State University, Manhattan, KS 66506 Louisiana Tech University, Ruston, LA 71272 University of Maryland, College Park, MD 20742 Boston University, Boston, MA 02215 Northeastern University, Boston, MA 02115 University of Michigan, Ann Arbor, MI 48109 Michigan State University, East Lansing, MI 48824 University of Mississippi, University, MS 38677 University of Nebraska, Lincoln, NE 68588 Princeton University, Princeton, NJ 08544 State University of New York, Buffalo, NY 14260 Columbia University, New York, NY 10027 University of Rochester, Rochester, NY 14627 State University of New York, Stony Brook, NY 11794 Brookhaven National Laboratory, Upton, NY 11973 Langston University, Langston, OK 73050 University of Oklahoma, Norman, OK 73019 Oklahoma State University, Stillwater, OK 74078 Brown University, Providence, RI 02912 University of Texas, Arlington, TX 76019 Southern Methodist University, Dallas, TX 75275 Rice University, Houston, TX 77005 University of Virginia, Charlottesville, VA 22901 University of Washington, Seattle, WA 98195 Instituto de Física Teórica Universidade Estadual Paulista, São Paulo Science and Technology Facilities Council: PP/D004284/1 Science and Technology Facilities Council: PP/E000487/1 Science and Technology Facilities Council: ST/H000992/1 Science and Technology Facilities Council: ST/H001166/1 Science and Technology Facilities Council: ST/K001604/1