1,211 research outputs found

    Determination of αs\alpha_s and heavy quark masses from recent measurements of R(s)R(s)

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    In this paper we compare recent experimental data for the total cross section σ(e+e−→hadrons)\sigma(e^+e^-\to{hadrons}) with the up-to-date theoretical prediction of perturbative QCD for those energies where perturbation theory is reliable. The excellent agreement suggests the determination of the strong coupling αs\alpha_s from the measurements in the continuum. The precise data from the charm threshold region, when combined with the recent evaluation of moments with three loop accurracy, lead to a direct determination of the short distance MSˉ\bar{\rm MS} charm quark mass. Our result for the strong coupling constant αs(4)(5GeV)=0.235−0.047+0.047\alpha_s^{(4)}(5 {GeV})=0.235^{+0.047}_{-0.047} corresponds to αs(5)(MZ)=0.124−0.014+0.011\alpha_s^{(5)}(M_Z)=0.124^{+0.011}_{-0.014}, for the charmed quark mass we find mc(mc)=1.304(27)m_c(m_c)=1.304(27). Applying the same approach to the bottom quark we obtain mb(mb)=4.191(51)m_b(m_b)=4.191(51) GeV. Whereas our result for αs(MZ)\alpha_s(M_Z) serves as a useful cross check for other more precise determinations, our values for the charm and bottom quark masses are more accurate than other recent analyses.Comment: 16 pages, minor change in numerical result for mb(mb

    Massive Quark Production in Electron Positron Annihilation to Order αs2\alpha_s^2

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    Recent analytical and numerical results for the three-loop polarization function allow to present a phenomenological analysis of the cross section for massive quark production in electron positron annihilation to order αs2\alpha_s^2. Numerical predictions based on fixed order perturbation theory are presented for charm and bottom production above 5 and 11.5 GeV, respectively. The contribution from these energy regions to α(MZ2)\alpha(M_Z^2), the running QED coupling constant at scale M_Z, are given. The dominant terms close to threshold, i.e. in an expansion for small quark velocity β\beta, are presented.Comment: 26 pages (Latex), 16 figures (Postscript

    137Cs in the meat of wild boars: a comparison of the impacts of Chernobyl and Fukushima

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    The impact of Chernobyl on the 137Cs activities found in wild boars in Europe, even in remote locations from the NPP, has been much greater than the impact of Fukushima on boars in Japan. Although there is great variability within the 137Cs concentrations throughout the wild boar populations, some boars in southern Germany in recent years exhibit higher activity concentrations (up to 10,000 Bq/kg and higher) than the highest 137Cs levels found in boars in the governmental food monitoring campaign (7900 Bq/kg) in Fukushima prefecture in Japan. The levels of radiocesium in boar appear to be more persistent than would be indicated by the constantly decreasing 137Cs inventory observed in the soil which points to a food source that is highly retentive to 137Cs contamination or to other radioecological anomalies that are not yet fully understood.CDC NIOSH Mountain and Plains Education and Research Center/T42OH009229-07NRC/NRC-HQ-12-G-38-004

    The Demographic Characteristics of 1860 New Ulm, Minnesota, Germans

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    Demand for an increase in ethnically oriented course materials led to this study of the 1860 New Ulm (Minnesota) German community as an example of ethnic migration and community establishment. The New Ulm German community was defined for the purposes of this study as the 698 German-born adult migrants living in New Ulm and its functionally connected area in 1860. Detailed information concerning the specific places of origin, migratory routes and sequences of intervening stops, and organizational networks of support was collected. A series of maps and graphs represents the migration patterns

    Surface Monitoring by Combination of an Optical Sensor and an Ultrasonic Scanning System

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    Nondestructive testing is a vital tool in the effort to ensure the quality of mechanically highly-loaded aero-engine parts. Nondestructive testing methods, such as eddy current and dye penetrant, are used to verify the surface condition of components, this condition greatly affecting operational safety and service life. Yet while these methods will readily detect small cracks, they fail to show the gradual changes in surface topology commonly associated with service wear
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