88 research outputs found

    Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2

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    We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.Comment: 17 pages, 10 figure

    Spin Structure of the Proton from Polarized Inclusive Deep-Inelastic Muon-Proton Scattering

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    We have measured the spin-dependent structure function g1pg_1^p in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.003<x<0.70.003 < x < 0.7 and 1GeV2<Q2<60GeV21 GeV^2 < Q^2 < 60 GeV^2. A next-to-leading order QCD analysis is used to evolve the measured g1p(x,Q2)g_1^p(x,Q^2) to a fixed Q02Q^2_0. The first moment of g1pg_1^p at Q02=10GeV2Q^2_0 = 10 GeV^2 is Γp=0.136±0.013(stat.)±0.009(syst.)±0.005(evol.)\Gamma^p = 0.136\pm 0.013(stat.) \pm 0.009(syst.)\pm 0.005(evol.). This result is below the prediction of the Ellis-Jaffe sum rule by more than two standard deviations. The singlet axial charge a0a_0 is found to be 0.28±0.160.28 \pm 0.16. In the Adler-Bardeen factorization scheme, Δg≃2\Delta g \simeq 2 is required to bring ΔΣ\Delta \Sigma in agreement with the Quark-Parton Model. A combined analysis of all available proton and deuteron data confirms the Bjorken sum rule.Comment: 33 pages, 22 figures, uses ReVTex and smc.sty. submitted to Physical Review

    Constraints on leptophobic Z' models from electroweak experiments

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    We study the constraints from updated electroweak data on the three leptophobic Z' models, the η{\eta} model with an appropriate U(1)â€Č−U(1)YU(1)'-U(1)_Y kinetic mixing, a Z' model motivated by the flipped SU(5) \times U(1) unification, and the phenomenological Z' model of Agashe, Graesser, and Hinchliffe. The Z−Zâ€ČZ-Z' mixing effects are parametrized in terms of a positive contribution to the TT parameter, TnewT_{new}, and the effective mass mixing parameter, Οˉ\bar{\xi}. All the theoretical predictions for the ZZ boson parameters, the WW boson mass and the observables in low-energy neutral current experiments are presented together with the standard model radiative corrections. The allowed region in the (Οˉ,Tnew\bar{\xi},T_{new}) plane is shown for the three models. The 95% CL lower limit on the heavier mass eigenstate Z2Z_2 is given as a function of the effective Z−Zâ€ČZ-Z' mixing parameter ζ\zeta.Comment: LaTeX, 22pages, 2 figures, corrected some typos. Final version to appear in Phys. Rev.

    Selective and “Veiled” Demarketing from the Perspective of Black Female Consumers

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    This study sheds light on the perspective of Black female consumers in regards to certain effects of marketing initiatives adopting the literature on demarketing as a framework. The context examined is their experience with the market of hair beauty and care. Media actions are analyzed along narrative interviews in order to understand the phenomenon. The findings reveal a structural dominant pattern which perpetuates the marginalized status of Black women’s natural traits. Emerging market initiatives point to movements concerning the visibility of such female consumers, who despite being eager to consume, have their demand discouraged. This suggests that they perceive a selective and veiled demarketing, as one of the results of marketing actions. The analysis invites for theoretical reflections on demarketing and veiled racism in Brazil

    Vegetal fibers in polymeric composites: a review

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    Chlorine-36 in seawater

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    Natural cosmogenic 36Cl found in seawater originates from spallation of atmospheric 40Ar, capture of secondary cosmic-ray neutrons by dissolved 35Cl, and river runoff which contains 36Cl produced in situ over the surface of the continents. The long residence time of chloride in the ocean and long half-life of 36Cl compared to the oceanic mixing time should result in a homogenous 36Cl/Cl ratio throughout the ocean. Production by neutron capture in the course of nuclear weapons testing should be insignificant averaged over the oceans as a whole, but may have led to regions of elevated 36Cl concentration. Previous attempts to measure the 36Cl/Cl ratio of seawater have been hindered by interferences, contamination, or insufficient analytic sensitivity. Here we report preliminary measurements on seawater samples, which demonstrate that the 36Cl/Cl ratio is 0.5 ± 0.3 × 10-15, in reasonable agreement with calculated contributions from the sources listed above

    The California verbal learning test-II: Normative data for two italian alternative forms

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    The aim of this study was to develop two versions of the California Verbal Learning Test-II (CVLT-II) and to administer them to a large sample of healthy controls representative of the normal Italian population for sex, age, and education levels. Two hundred and eighty healthy controls entered the study and were randomly assigned to one of the two forms of CVLT-II. No significant difference emerged between the two forms. Considering the significant weight of sex, age and education level, a regression model was developed through which it was possible to calculate the adjusted scores. The lower tolerance limits were also calculated
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