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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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- Kendall, A, et al.
(författare)
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Weight loss on a low-fat diet: consequence of the imprecision of the control of food intake in humans
- 1991
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Ingår i: American Journal of Clinical Nutrition. ; 53, s. 1124-1129
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Tidskriftsartikel (refereegranskat)abstract
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853. This study examined the degree to which humans compensate for a reduction in dietary fat by increasing energy intake. Thirteen females were randomly assigned to either a low-fat diet (20-25% of calories as fat) or a control diet (35-40% fat) for 11 wk. After a 7-wk washout period, the conditions were reversed for another 11 wk. Energy intake on the low-fat diet gradually increased by 0.092 kJ/wk resulting in a total caloric compensation of 35% by the end of the 11-wk treatment period. This failure to compensate calorically on the low-fat diet resulted in a deficit of 1.22 kJ/d and a weight loss of 2.5 kg in 11 wk, twice the amount of weight lost on the control diet. These results demonstrate that body weight can be lost merely by reducing the fat content of the diet without the need to voluntarily restrict food intake. PMID: 2021123 [PubMed - indexed for MEDLINE]
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