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- 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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| 4. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 9. |
- Otamiri, JC, et al.
(författare)
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Ammoxidation of Toluene by YBa2Cu3O6 + x and Copper Oxides. Activity and XPS Studies
- 1990
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Ingår i: Applied Catalysis. - 0166-9834. ; 65:1, s. 159-174
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic activities of YBa2Cu3O6+x and copper oxides have been studied in the ammoxidation of toluene. At low oxygen pressures, over YBa2Cu3O6+x selective ammoxidation to benzonitrile occurs, whereas at high pressures, only total combustion of toluene to carbon oxides is observed. X-ray photoelectron spectroscopy (XPS) analysis of YBa2Cu3O6+x catalysts indicates predominance of Cu(I) states under partial ammoxidation conditions, while under total oxidation conditions, Cu(II) states are predominant. Comparison with the catalytic performance of copper oxide catalysts shows that differences do exist. The catalysis by YBa2Cu3O6+x is greatly influenced by the oxygen content of the bulk material despite its surface composition.
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| 10. |
- Otamiri, JC, et al.
(författare)
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Effect of Zn Substitutions in YBa2Cu3O6 + x Phases on Reactivity during the Ammoxidation of Toluene
- 1991
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Ingår i: Journal of the Chemical Society, Faraday Transactions. - : Royal Society of Chemistry (RSC). - 0956-5000 .- 1364-5455. ; 87:8, s. 1265-1271
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Tidskriftsartikel (refereegranskat)abstract
- Zn substitution in Y-Ba-Cu-O phases influences the catalytic ammoxidation of toluene. The activity for formation of both benzonitrile and CO2 at low and high O2 pressures, respectively, decreases strongly with increasing Zn content up to 4%. Above this substitution level, the activity, however, increases slightly. Characterisations of the surface by XPS and of the bulk by XRD analysis, indicate the presence of overlayers on the catalysts. In these overlayers, irrespective of the Zn content of catalysts, Cu1 states predominate at low O2 pressure and Cu11 at high pressure. These states are associated with selective and non-selective properties, respectively. The activity of the catalysts shows a general tendency to increase with surface copper concentrations as found from XPS studies. However, strong deviations from linearity indicate that the activity of the overlayer is greatly influenced by the bulk acting as a support.
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