| 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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| 3. |
- Termeer, Catrien J. A. M., et al.
(författare)
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Institutions and the resilience of biobased production systems : the historical case of livestock intensification in the Netherlands
- 2019
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Ingår i: Ecology & Society. - : The Resilience Alliance. - 1708-3087. ; 24:4
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Tidskriftsartikel (refereegranskat)abstract
- Disconnects between farming and urban systems are widely seen as impairing the resilience of biobased production systems (BBPSs). However, the institutional mechanisms that underlie these resilience problems are not well understood. In this explorative paper, which integrates elements from institutional and resilience theory, we develop a framework to analyze how institutionally shaped patterns of connects and disconnects affect the resilience of BBPs along the dimensions of robustness, adaptability, and transformability. This framework is applied to the historical case of pig livestock intensification in the Netherlands from 1870 to 2017. The case shows that institutions, successfully established in earlier periods, shape connects and disconnects in subsequent periods, thereby enabling and constraining resilience. A combination of perturbations, institutional layering, and shifts in ideational power is an important institutional mechanism for resilience. We conclude that building resilience requires a variety of reconnecting institutions and refraining from a focus on local reconnects or certification only.
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