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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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| 2. |
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| 3. |
- Londo, Marc, et al.
(författare)
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Eyes on the track, mind on the horizon: The REFUEL EU Road Map for biofuels
- 2008
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Ingår i: Proceedings of the 16th European Biomass Conference & Exhibition - From research to industry and markets, Feria Valencia, Spain, 2-6 June 2008.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The current hot debate on biofuels calls for a balanced and realistic long-term strategy for biofuels. The REFUEL project provides several ingredients for such a strategy. Analyses in this project indicate that domestically produced biofuels can cover a significant share of EU fuel demand in the coming decades, with the EU-12 new member states and Ukraine as most promising regions. This potential can be realised with residual streams and on existing agricultural land, without conversion of e.g. nature reserves. Second-generation biofuels are essential for the long-term success of biofuels due to their superior performance in many ways. But generally, the key challenge for the near future would be how to enhance the development of biofuels in a responsible way, i.e. stimulating the production chains with the best performance, and preventing negative impacts e.g., by paying careful attention to possible system impacts of biofuel production such as indirect land use changes and rising food prices. Finally, 2nd generation biofuels require specific policy: the precursor role of 1st generation is overrated, both in technical terms as well as in their role as market precursors. When it comes to synergies, 2nd generation biofuels might benefit more from other developments in the energy sector, such as initiatives in co-firing of biomass for (heat and) power, than from 1st generation biofuels, also because of the public resistance that the latter induce.
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| 4. |
- Londo, Marc, et al.
(författare)
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REFUEL: an EU road map for biofuels
- 2007
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Ingår i: Proceedings of the Risø International Energy Conference 2007, 22-24 May.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A successful mid-term development of biofuels calls for a robust road map. REFUEL assesses inter alia least-cost biofuel chain options, their benefits, outlines the technological, legislative and other developments that should take place, and evaluate different policy strategies for realisation. Some preliminary conclusions of the project are discussed here. There is a significant domestic land potential for energy crops in the EU, which could supply between one quarter and one third of gasoline and diesel demand by 2030 if converted into advanced biofuels. A biomass supply of 8 to 10 EJ of primary energy could be available at costs around or below 3 €/GJ. However, the introduction of advanced biofuel options may meet a considerable introductory cost barrier, which will not be overcome when EU policy is oriented to the introduction of biofuels at least cost. Therefore, conventional biodiesel en ethanol may dominate the market for decades to come, unless biofuels incentives are differentiated, e.g. on the basis of the differences in greenhouse gas performance among biofuels.The introduction of advanced biofuels may also be enhanced by creating stepping stones or searching introduction synergies. A stepping stone can be the short-term development of lignocellulosic biomass supply chains for power generation by co-firing; synergies can be found between advanced FT-diesel production and hydrogen production for the fuel cell.
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