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- Schael, S., et al.
(author)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Research review (peer-reviewed)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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| 4. |
- García, A., et al.
(author)
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Uniformity and mechanical properties of dense asphalt concrete with steel wool fibers
- 2013
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In: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 43, s. 107-117
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Journal article (peer-reviewed)abstract
- Fibers in asphalt concrete are known for enhancing its strength and fatigue characteristics while increasing ductility. Additionally, fibers may increase the dynamic modulus, moisture resistance, creep compliance, rutting and freeze-thaw resistance of asphalt concrete, preventing the formation and propagation of cracks. The addition of fibers may influence the properties of the material, but it is not clear how is this influence, and which are the optimum amount, length and diameter of fibers needed for not having a negative impact on the mixture. For this reason, fibers (steel wool) distribution and their effect on the porosity and electrical conductivity of dense asphalt concrete have been studied. With that purpose, 25 different mixtures, with the same aggregates gradation and amount of bitumen, but with two different lengths of fibers, four different percentages, and four different diameters of steel wool have been built. Results show that long and thin fibers produce many clusters and a poor distribution, while short and thick fibers disperse very well in the mixture. It was also observed that fibers can be seriously damaged during the mixing and compaction processes. Finally, it has been found that steel wool fibers do not have a relevant influence on the particle loss resistance and flexural strength of dense asphalt concrete.
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