2,829 research outputs found

    State Level Earned Income Tax Credit’s Effects on Race and Age: An Effective Poverty Reduction Policy

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    In this paper, I analyze the effectiveness of state level Earned Income Tax Credit programs on improving of poverty levels. I conducted this analysis for the years 1991 through 2011 using a panel data model with fixed effects. The main independent variables of interest were the state and federal EITC rates, minimum wage, gross state product, population, and unemployment all by state. I determined increases to the state EITC rates provided only a slight decrease to both the overall white below-poverty population and the corresponding white childhood population under 18, while both the overall and the under-18 black population for this category realized moderate decreases in their poverty rates for the same time period. I also provide a comparison of the effectiveness of the state level EITCs and minimum wage at the state level over the same time period on these select demographic groups

    Asymmetric Quark/Antiquark Hadronization in e+e- Annihilation

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    We point out that the fragmentation of a strange quark into nucleons versus antinucleons is not necessarily identical Dp/s(z,Q2)Dpˉ/s(z,Q2)D_{p/s}(z,Q^2) \neq D_{\bar p/s}(z,Q^2), even though the perturbative contributions from gluon splitting and evolution are ppˉp \leftrightarrow \bar p symmetric. The observation of such asymmetries in the hadronization of strange and other heavy quarks can provide insight into the nonperturbative mechanisms underlying jet fragmentation in QCD.Comment: Latex, 12 page

    Interlayer c-axis transport in the normal state of cuprates

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    A theoretical model of c-axis transport properties in cuprates is proposed. Inter-plane and in-plane charge fluctuations make hopping between planes incoherent and diffusive (the in-plane momentum is not conserved after tunneling). The non-Drude optical conductivity σc(ω)\sigma_c(\omega) and the power-law temperature dependence of the {\it dc} conductivity are generically explained by the strong fluctuations excited in the process of tunneling. Several microscopic models of the charge fluctuation spectrum are considered.Comment: 8 page

    Axial Vector Coupling Constant in Chiral Colour Dielectric Model

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    The axial vector coupling constants of the β\beta decay processes of neutron and hyperon are calculated in SU(3) chiral colour dielectric model (CCDM). Using these axial coupling constants of neutron and hyperon, in CCDM we calculate the integrals of the spin dependent structure functions for proton and neutron. Our result is similar to the results obtained by MIT bag and Cloudy bag models.Comment: 9 pages, Latex file, no figure, to appear in Phys. Rev.

    Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model (I) -- phenomenological predictions --

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    Theoretical predictions are given for the light-flavor sea-quark distributions including the strange quark ones on the basis of the flavor SU(3) version of the chiral quark soliton model. Careful account is taken here of the SU(3) symmetry breaking effects due to the mass difference between the strange and nonstrange quarks. This effective mass difference Δms\Delta m_s between the strange and nonstrange quarks is the only one parameter necessary for the flavor SU(3) generalization of the model. A particular emphasis of study is put on the {\it light-flavor sea-quark asymmetry} as exemplified by the observables dˉ(x)uˉ(x),dˉ(x)/uˉ(x),Δuˉ(x)Δdˉ(x)\bar{d} (x) - \bar{u} (x), \bar{d} (x) / \bar{u} (x), \Delta \bar{u} (x) - \Delta \bar{d} (x) as well as on the {\it particle-antiparticle asymmetry} of the strange quark distributions represented by s(x)sˉ(x),s(x)/sˉ(x),Δs(x)Δsˉ(x)s (x) - \bar{s} (x), s (x) / \bar{s} (x), \Delta s (x) - \Delta \bar{s} (x) etc. As for the unpolarized sea-quark distributions, the predictions of the model seem qualitatively consistent with the available phenomenological information provided by the NMC data for dˉ(x)uˉ(x)\bar{d} (x) - \bar{u} (x), the E866 data for dˉ(x)/uˉ(x)\bar{d} (x) / \bar{u} (x), the CCFR data and Barone et al.'s fit for s(x)/sˉ(x)s (x) / \bar{s} (x) etc. The model is shown to give several unique predictions also for the spin-dependent sea-quark distribution, such that Δs(x)Δsˉ(x)0\Delta s (x) \ll \Delta \bar{s}(x) \lesssim 0 and Δdˉ(x)<0<Δuˉ(x)\Delta \bar{d}(x) < 0 < \Delta \bar{u}(x), although the verification of these predictions must await more elaborate experimental investigations in the near future.Comment: 36 pages, 20 EPS figures. The revised version accepted for publication in Phys. Rev. D. The title has been changed, and the body of the paper has been divided into two pieces, i.e.. the present one which discusses the main phenomenological predictions of the model and the other one which describes the detailed formulation of the flavor SU(3) chiral quark soliton model to predict light-flavor quark and antiquark distribution functions in the nucleo

    Flavour and Spin of the Proton and the Meson Cloud

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    We present a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon. It can be applied in the framework of convolution formalism to the deep-inelastic structure functions (quark distributions) of the nucleon viewed as a system composed of virtual 'mesons' and 'baryons'. Pseudoscalar and vector mesons as well as octet and decuplet baryons are included. In contrast to many approaches in the literature the present approach ensures charge and momentum conservation by the construction. We present not only spin averaged splitting functions but also helicity dependent ones, which can be used to study the spin content of the nucleon. The cut-off parameters of the underlying form factors for different vertices are determined from high-energy particle production data. This information allows one to calculate the flavour and spin content of the nucleon. The value of the Gottfried Sum Rule obtained from our model (S_G = 0.224) nicely agrees with that obtained by the NMC. In addition, we calculate the x-dependence of the \bar d - \bar u asymmetry and get an impressive agreement with a recent fit of Martin-Stirling-Roberts. The calculated axial coupling constants for semileptonic decays of the octet baryons agree with the experimental data already with SU(6) wave function for the bare nucleon. Although we get improvements for the Ellis-Jaffe Sum Rules for the proton and neutron in comparison to the naive quark model, the MCM is not sufficient to reproduce the experimental data.Comment: written in ReVTex, 53 pages, 11 PS-figure

    The Spin Structure of the Nucleon

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    We present an overview of recent experimental and theoretical advances in our understanding of the spin structure of protons and neutrons.Comment: 84 pages, 29 figure

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
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