| 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. |
- Koyi, Hemin A., et al.
(författare)
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The mechanical relationship between strike-slip faults and salt diapirs in the Zagros fold-thrust belt
- 2008
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Ingår i: Journal of the Geological Society. - 0016-7649 .- 2041-479X. ; 165, s. 1031-1044
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Tidskriftsartikel (refereegranskat)abstract
- Analogue models are used to study the mechanical relationship between basement strike-slip faults and salt diapirs. Displacement along a strike-slip fault in 1 g models resulted in extension along pre-existing jogs and the formation of oblique extensional faults, where reactive diapirs were triggered in some models. In the centrifuge models prescribed cuts, simulating pre-existing structures, were reactivated during simple shear deformation of the models, resulting in formation of pull-apart basins, which were intruded by diapirs. The models show that because of the low ratio of salt to overburden thickness in the Zagros (0.15-0.35). It is unlikely that diapirs have formed solely, if at all as a result of movement along basement strike-slip faults. Two mechanisms are suggested. First, pre-kinematic thin overburden and continuous movement along a releasing bend in the cover units may have triggered some of the diapirs in the Zagros, which were later downbuilt to their current geometry by additional sedimentation. Second, movement along the strike-slip faults (e.g. the Kazerun and Mangarak faults) induced oblique movement along NW-SE Zagros structures (folds or thrusts) resulting in the formation of pull-part basins where diapirs were eventually intruded. Fault plane solution of shallow earthquakes supports the second scenario, which is also in agreement with previous interpretations that some of the salt diapirs associated with basement faults are younger than Zagros shortening and young southwestwards.
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