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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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- Blair, SN, et al.
(författare)
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Body weight change, all-cause mortality, and cause-specific mortality in the Multiple Risk Factor Intervention Trial
- 1993
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Ingår i: Annals of Internal Medicine. ; 119, s. 749-757
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Tidskriftsartikel (refereegranskat)abstract
- Cooper Institute for Aerobics Research, Dallas, Texas. OBJECTIVE: To evaluate the relation between weight variability and death in high-risk, middle-aged men participating in the Multiple Risk Factor Intervention Trial (MRFIT). DESIGN: Cohort study with 3.8 years of follow-up. SETTING: Multicenter, collaborative, primary prevention trial conducted at 22 clinical centers in the United States. PARTICIPANTS: Men (n = 10,529) who were 35 to 57 years old at baseline and who were in the upper 10% to 15% of risk for coronary heart disease because of smoking, high blood pressure, and elevated cholesterol level. Participants were seen at least annually for 6 to 7 years for medical evaluations in study clinical centers. MEASUREMENTS: Death from cardiovascular disease (228 deaths) and from all causes (380 deaths). RESULTS: The primary measure of weight variability was the intrapersonal standard deviation of weight (ISD), which was calculated from measured weights obtained at clinic visits during a 6- to 7-year period. All-cause death rates per 1000 person-years of follow-up across ISD quartiles were 8.28, 8.25, 10.57, and 11.07 from the first to fourth quartiles, respectively. After adjusting for baseline risk factors associated with weight change, the relative risk for all-cause mortality in the fourth compared with the first quartile was 1.64 (95% CI, 1.21 to 2.23). Cardiovascular death and ISD showed a similar pattern. The association between weight change and death was not observed in the heaviest men. CONCLUSION: Greater weight variability was associated with a greater risk for cardiovascular disease and all-cause mortality in some types of high-risk men. PMID: 8363210 [PubMed - indexed for MEDLINE]
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