| 1. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Abreu, P, et al.
(författare)
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First study of the interference between initial and final state radiation at the Z resonance
- 1996
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 72:1, s. 31-38
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The interference between initial and final state radiation in the process e(+)e(-) --> mu(+)mu(-) at root s approximate to M(Z) has been studied by measuring the forward-backward asymmetry as a function of the acoplanarity angle between the final state mu
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| 4. |
- Abreu, P, et al.
(författare)
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Kaon interference in the hadronic decays of the Z(0)
- 1996
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 379:1-4, s. 330-340
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The first measurement of like-sign charged kaon correlations in hadronic decays of the Z(0) is presented, based on data collected by the DELPHI detector. The charged kaons are identified by means of ring imaging Cherenkov detectors. A significant enhancem
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| 5. |
- Abreu, P, et al.
(författare)
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Measurement of inclusive K*(0)(892), phi(1020) and K-2*(0)(1430) production in hadronic Z decays
- 1996
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 73:1, s. 61-72
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The inclusive production of the neutral vector mesons K-*0(892) and phi(1020), and of the tensor meson K-2(*0)(1430), in hadronic decays of the Z has been mea sured by the DELPHI detector at LEP. The average production rates per hadronic Z decay have been
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| 6. |
- Abreu, P, et al.
(författare)
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Updated precision measurement of the average lifetime of B hadrons
- 1996
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 377:1-3, s. 195-204
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and syste
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| 7. |
- Adam, W, et al.
(författare)
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Production of Sigma(0) and Omega(-) in Z decays
- 1996
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 70:3, s. 371-381
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Reconstructed ii baryon decays and photon conversions in DELPHI are used to measure the Sigma(0) production rate from hadronic Z(0) decays at LEP. The number of Sigma(0) decays per hadronic Z decay is found to be: > = 0.07
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| 8. |
- Adam, W, et al.
(författare)
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Search for anomalous production of single photons at root s=130 and 136 GeV
- 1996
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 380:3-4, s. 471-479
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This letter reports the results of the measurement of single photon production in the reaction e(+)e(-) --> gamma+ invisible particles at centre-of-mass energies root s = 130 and 136 GeV and an integrated luminosity of 5.83 pb(-1), collected with the DELP
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| 9. |
- Adam, W, et al.
(författare)
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Study of rare b decays with the DELPHI detector at LEP
- 1996
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 72:2, s. 207-220
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Rare decays of beauty particles were studied in several charmless modes using the data collected with the DELPHI detector at LEP from 1991 to 1994. These decays are mediated by both tree level b-->u and one-loop penguin b-->s, d transitions. Evidence for
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| 10. |
- Abreu, P, et al.
(författare)
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A precise measurement of the B-d(0) meson lifetime using a new technique
- 1997
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 74:1, s. 19-32
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- From data recorded by DELPHI between 1991 and 1994, which corresponds to 3.2 million hadronic Z(0) decays, a measurement of the <(B-d(0))over bar> meson lifetime, based on the inclusive reconstruction of 3520 +/- 150 semileptonic decays of the type <(B-d(
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