| 1. |
- 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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| 2. |
- Abreu, P, et al.
(författare)
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Search for composite and exotic fermions at LEP 2
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 8:1, s. 41-58
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb(-1) at a
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| 3. |
- Abreu, P, et al.
(författare)
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Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 7:4, s. 595-607
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NL
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| 4. |
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| 5. |
- Abreu, P, et al.
(författare)
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A precise measurement of the partial decay width ratio R-b(0) = Gamma(b(b)over-bar)/Gamma(had)
- 1999
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 10:3, s. 415-442
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The partial decay width of the Z to b (b) over bar quark pairs has been measured by the DELPHI detector at LEP using data taken in the years 1992 to 1995. Decays of b-hadrons were tagged by several methods using tracks with large impact parameters and/or
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| 6. |
- Abreu, P, et al.
(författare)
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A search for eta '(c) production in photon-photon fusion at LEP
- 1998
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 441:1-4, s. 479-490
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A search for the production of the eta(c)' meson, the first radial excitation of the ground state of charmonium eta(c)(2980), in the photon-photon fusion reaction at LEP has been performed using the data collected by the DELPHI detector during 1992-1996.
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| 7. |
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| 8. |
- Abreu, P, et al.
(författare)
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A search for invisible Higgs bosons produced in e(+)e(-) interactions at LEP 2 energies
- 1999
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Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 459:1-3, s. 367-381
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Searches for HZ production with the Higgs boson decaying into an invisible final state have been performed with the data collected by the DELPHI experiment up to the centre-of-mass energy of 183 GeV. The hadronic and muon pair final states of the Z boson
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| 9. |
- Abreu, P, et al.
(författare)
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A study of the Lorentz structure in tau decays
- 2000
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER-VERLAG. - 1434-6044. ; 16:2, s. 229-252
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a measurement of the Michel parameters, eta, rho, xi, xi delta, and the average v(tau) helicity, h(nu tau), in tau lepton decays together with the first measurement of the tensor coupling in the weak charged current. The tau(+)tau(-)
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| 10. |
- Abreu, P, et al.
(författare)
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Consistent measurements of alpha(s) from precise oriented event shape distributions
- 2000
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Ingår i: EUROPEAN PHYSICAL JOURNAL C. - : SPRINGER VERLAG. - 1434-6044. ; 14:4, s. 557-584
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Tidskriftsartikel (refereegranskat)abstract
- An updated analysis using about 1.5 million events recorded at root s = M-Z with the DELPHI detector in 1994 is presented. Eighteen infrared and collinear safe event shape observables are measured as a function of the polar angle of the thrust. axis. The
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