https://doi.org/10.1140/epjc/s10052-009-1123-y
Regular Article - Experimental Physics
Correlations between polarisation states of W particles in the reaction e − e +→W − W + at LEP2 energies 189–209 GeV
1
Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011-3160, USA
2
Physics Department, Universiteit Antwerpen, Universiteitsplein 1, 2610, Antwerpen, Belgium
3
IIHE, ULB-VUB, Pleinlaan 2, 1050, Brussels, Belgium
4
Physics Laboratory, University of Athens, Solonos Str. 104, 10680, Athens, Greece
5
Department of Physics, University of Bergen, Allégaten 55, 5007, Bergen, Norway
6
Dipartimento di Fisica, Università di Bologna and INFN, Viale C. Berti Pichat 6/2, 40127, Bologna, Italy
7
Centro Brasileiro de Pesquisas Físicas, rua Xavier Sigaud 150, 22290, Rio de Janeiro, Brazil
8
Inst. de Física, Univ. Estadual do Rio de Janeiro, rua São Francisco Xavier 524, Rio de Janeiro, Brazil
9
Collège de France, Lab. de Physique Corpusculaire, IN2P3-CNRS, 75231, Paris Cedex 05, France
10
CERN, 1211, Geneva 23, Switzerland
11
Institut de Recherches Subatomiques, IN2P3–CNRS/ULP-BP20, 67037, Strasbourg Cedex, France
12
DESY-Zeuthen, Platanenallee 6, 15735, Zeuthen, Germany
13
Institute of Nuclear Physics, N.C.S.R. Demokritos, P.O. Box 60228, 15310, Athens, Greece
14
FZU, Inst. of Phys. of the C.A.S. High Energy Physics Division, Na Slovance 2, 182 21, Praha 8, Czech Republic
15
Dipartimento di Fisica, Università di Genova and INFN, Via Dodecaneso 33, 16146, Genova, Italy
16
Institut des Sciences Nucléaires, IN2P3-CNRS, Université de Grenoble 1, 38026, Grenoble Cedex, France
17
Helsinki Institute of Physics and Department of Physical Sciences, P.O. Box 64, 00014, University of Helsinki, Finland
18
Joint Institute for Nuclear Research, Dubna, Head Post Office, P.O. Box 79, 101 000, Moscow, Russian Federation
19
Institut für Experimentelle Kernphysik, Universität Karlsruhe, Postfach 6980, 76128, Karlsruhe, Germany
20
Institute of Nuclear Physics PAN, Ul. Radzikowskiego 152, 31142, Krakow, Poland
21
Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, 30055, Krakow, Poland
22
LAL, Univ Paris-Sud, CNRS/IN2P3, Orsay, France
23
School of Physics and Chemistry, University of Lancaster, Lancaster, LA1 4YB, UK
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LIP, IST, FCUL, Av. Elias Garcia, 14-1º, 1000, Lisboa Codex, Portugal
25
Department of Physics, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX, UK
26
Dept. of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ, UK
27
LPNHE, IN2P3-CNRS, Univ. Paris VI et VII, Tour 33 (RdC), 4 place Jussieu, 75252, Paris Cedex 05, France
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Department of Physics, University of Lund, Sölvegatan 14, 223 63, Lund, Sweden
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Université Claude Bernard de Lyon, IPNL, IN2P3-CNRS, 69622, Villeurbanne Cedex, France
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Dipartimento di Fisica, Università di Milano and INFN-MILANO, Via Celoria 16, 20133, Milan, Italy
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Dipartimento di Fisica, Univ. di Milano-Bicocca and INFN-MILANO, Piazza della Scienza 3, 20126, Milan, Italy
32
IPNP of MFF, Charles Univ., Areal MFF, V Holesovickach 2, 180 00, Praha 8, Czech Republic
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NIKHEF, Postbus 41882, 1009 DB, Amsterdam, The Netherlands
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Physics Department, National Technical University, Zografou Campus, 15773, Athens, Greece
35
Physics Department, University of Oslo, Blindern, 0316, Oslo, Norway
36
Dpto. Fisica, Univ. Oviedo, Avda. Calvo Sotelo s/n, 33007, Oviedo, Spain
37
Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
38
Dipartimento di Fisica, Università di Padova and INFN, Via Marzolo 8, 35131, Padua, Italy
39
Rutherford Appleton Laboratory, Chilton, Didcot, OX11 OQX, UK
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Dipartimento di Fisica, Università di Roma II and INFN, Tor Vergata, 00173, Rome, Italy
41
Dipartimento di Fisica, Università di Roma III and INFN, Via della Vasca Navale 84, 00146, Rome, Italy
42
DAPNIA/Service de Physique des Particules, CEA-Saclay, 91191, Gif-sur-Yvette Cedex, France
43
Instituto de Fisica de Cantabria (CSIC-UC), Avda. los Castros s/n, 39006, Santander, Spain
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Inst. for High Energy Physics, Serpukov P.O. Box 35, Protvino, Moscow Region, Russian Federation
45
J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
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Laboratory for Astroparticle Physics, University of Nova Gorica, Kostanjeviska 16a, 5000, Nova Gorica, Slovenia
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Department of Physics, University of Ljubljana, 1000, Ljubljana, Slovenia
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Fysikum, Stockholm University, Box 6730, 113 85, Stockholm, Sweden
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Dipartimento di Fisica Sperimentale, Università di Torino and INFN, Via P. Giuria 1, 10125, Turin, Italy
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INFN, Sezione di Torino and Dipartimento di Fisica Teorica, Università di Torino, Via Giuria 1, 10125, Turin, Italy
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Dipartimento di Fisica, Università di Trieste and INFN, Via A. Valerio 2, 34127, Trieste, Italy
52
Istituto di Fisica, Università di Udine and INFN, 33100, Udine, Italy
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Univ. Federal do Rio de Janeiro, C.P. 68528 Cidade Univ., Ilha do Fundão, 21945-970, Rio de Janeiro, Brazil
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Department of Radiation Sciences, University of Uppsala, P.O. Box 535, 751 21, Uppsala, Sweden
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IFIC, Valencia-CSIC, and D.F.A.M.N., U. de Valencia, Avda. Dr. Moliner 50, 46100, Burjassot (Valencia), Spain
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Institut für Hochenergiephysik, Österr. Akad. d. Wissensch., Nikolsdorfergasse 18, 1050, Vienna, Austria
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Inst. Nuclear Studies and University of Warsaw, Ul. Hoza 69, 00681, Warsaw, Poland
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University of Warwick, Coventry, CV4 7AL, UK
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Fachbereich Physik, University of Wuppertal, Postfach 100 127, 42097, Wuppertal, Germany
* e-mail: jan.timmermans@cern.ch
Received:
26
February
2009
Revised:
14
June
2009
Published online:
1
September
2009
In a study of the reaction e
−
e
+→W
−
W
+ with the DELPHI detector, the probabilities of the two W particles occurring in the joint polarisation states transverse–transverse (TT), longitudinal–transverse plus transverse–longitudinal (LT) and longitudinal–longitudinal (LL) have been determined using the final states (l=e,μ). The two-particle joint polarisation probabilities, i.e. the spin density matrix elements ρ
TT
, ρ
LT
, ρ
LL
, are measured as functions of the W
− production angle,
, at an average reaction energy of 198.2 GeV. Averaged over all
, the following joint probabilities are obtained:
These results are in agreement with the Standard Model predictions of 63.0%, 28.9% and 8.1%, respectively. The related polarisation cross-sections σ
TT
, σ
LT
and σ
LL
are also presented.
© Springer-Verlag , 2009