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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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- Norrgren, L, et al.
(författare)
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Effects of potential xenoestrogens (DEHP, nonylphenol and PCB) on sexual differentiation in juvenile Atlantic salmon (Salmo salar)
- 1999
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Ingår i: Aquatic Ecosystem Health & Management. - : Michigan State University Press. - 1463-4988 .- 1539-4077. ; 2:3, s. 311-317
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Tidskriftsartikel (refereegranskat)abstract
- The effects of 17β-estradiol and potential xenoestrogens were investigated on Atlantic salmon (Salmo salar). Juvenile salmon fed diets containing 15 and 30 mg 17β-estradiol kg−1 food for 4 weeks after yolk-sac resorption differentiated into 88 and 100% phenotypic females, respectively. The reference group, fed uncontaminated food, consisted of 49% females. A significant overrepresentation of phenotypic females (64%) was recorded in the group fed 1500 mg di-2-ethylhexyl phthalate kg−1 food. Atlantic salmon fed diets contaminated with nonylphenol showed no differences in sex ratios compared with the control group. A significantly increased liver somatic index was detected for groups exposed to diets contaminated with 15 and 30 mg 17β-estradiol, 300 mg nonylphenol or 1500 mg di-2-ethylhexyl phthalate kg−1 food. Intraperitoneal injections of nonylphenol, di-2-ethylhexyl phthalate, or polychlorinated biphenyls 58, 104, 112 and 188 did not induce synthesis of vitellogenin which is considered to be a hallmark for estrogenic activity in in vivo testing. Therefore, in vivo assays, that is, intraperitoneal injection, can not always predict how endocrine processes in organisms are affected by pollutants.
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