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- Schael, S, et al.
(author)
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Precision electroweak measurements on the Z resonance
- 2006
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In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Research review (peer-reviewed)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. |
- Birney, Ewan, et al.
(author)
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Prepublication data sharing
- 2009
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7261, s. 168-170
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Journal article (peer-reviewed)abstract
- Rapid release of prepublication data has served the field of genomics well. Attendees at a workshop in Toronto recommend extending the practice to other biological data sets.
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| 3. |
- Chen, W, et al.
(author)
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Fabrication and luminescence of ZnS : Mn2+ nanoflowers
- 2005
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In: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 0000-0000. ; 5:9, s. 1309-1322
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Journal article (peer-reviewed)abstract
- Visually striking nanoflowers composed of ZnS:Mn2+ nanoparticles are prepared and characterized. The configurations of these fractal structures are very sensitive to both the pH values of the particle solutions from which they are precipitated and the substrates on which they are deposited. At pH 2.2, the fractal structures resemble trees without leaves; at pH 7.7, they are tree-like with four arms and at pH 11.0 they resemble trees with six arms. High resolution transmission microscopy reveals that the nanoflowers are composed of ZnS:Mn2+ nanoparticles of 2-5 nm in size. X-ray photoelectron spectral data indicate that the sample compositions of nitrogen, chlorine, and sulfur vary gradually with pH values of the solutions. These changes may have an impact on both the fractal configuration and the luminescence properties. The emission spectra of the particle solutions at pH values of 2.2 and 11.0 are similar with the emission maximum at 475 nm. As the pH value approaches 7.7, the emission spectral maximum shifts to longer wavelengths. At a pH value of 7.7, the emission peak wavelength is the reddest, 520 nm. The emission peak of the nanoflowers at a pH value of 9.3 is 510 nm, while the emission spectrum of the nanoflowers at 5.2 has two peaks at 500 nm and 440 nm, respectively. These blue-green emissions are attributed to defects and are the dominant luminescence from the nanoflowers. The emission from Mn2+ dopant is only observed in the delayed spectra of the fractal solid samples.
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