589 research outputs found

    Dynamical masses of quarks in quantum chromodynamics

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    Using Dyson-Schwinger equations we obtain an ultraviolet asymptotics for the dynamical mass of quark in QCD. We also determine a numerical value for the \pi meson decay constant f_\pi.Comment: Electronic version of the published paper, latex, 4 page

    Momentum dependent quark mass in two-point correlators

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    A momentum dependent quark mass may be incorporated into a quark model in a manner consistent with dynamically broken chiral symmetry. We use this to study the high Q2Q^2 behavior of the vector, axialvector, scalar and pseudoscalar two-point correlation functions. Expanding the results to order 1/Q61/Q^6, we show the correspondence between the dynamical quark mass and the vacuum condensates which appear in the operator product expansion of QCD. We recover the correct leading logarithmic Q2Q^2 dependence of the various terms in the OPE, but we also find substantial subleading corrections which are numerically huge in a specific case. We conclude by using the vector minus axialvector correlator to estimate the π+−π0\pi^+ - \pi^0 electromagnetic mass difference.Comment: 18 pages, LaTeX, figures in accompanying uuencoded postscript file. Published version. References adde

    Vertices and the CJT Effective Potential

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    The Cornwall-Jackiw-Tomboulis effective potential is modified to include a functional dependence on the fermion-gauge particle vertex, and applied to a quark confining model of chiral symmetry breaking.Comment: 10 pages (latex), PURD-TH-93-1

    Implementing Collective Bargaining Enabling Legislation : Washington Universities Join the Party

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    In 2002, Washington passed enabling legislation that, for the first time, expressly granted to the faculty at the state’s public four-year colleges and universities the right to bargain regarding their terms and conditions of employment. To date, faculty at four of the state’s six four-year public institutions of higher education have formed unions, and two of those unions have negotiated first contracts. This paper describes the history of that process, the legal framework in which it took place, and the issues of greatest importance at the bargaining table

    Calculation of the Chiral Lagrangian Coefficients from the Underlying Theory of QCD: A Simple Approach

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    We calculate the coefficients in the chiral Lagrangian approximately from QCD based on a previous study of deriving the chiral Lagrangian from the first principles of QCD in which the chiral Lagrangian coefficients are defined in terms of certain Green's functions in QCD. We first show that, in the large N(c)-limit, the anomaly part contributions to the coefficients are exactly cancelled by certain terms in the normal part contributions, and the final results of the coefficients only concern the remaining normal part contributions depending on QCD interactions. We then do the calculation in a simple approach with the approximations of taking the large-N(c) limit, the leading order in dynamical perturbation theory, and the improved ladder approximation, thereby the relevant Green's functions are expressed in terms of the quark self energy. By solving the Schwinger-Dyson equation for the quark self energy, we obtain the approximate QCD predicted coefficients and the quark condensate which are consistent with the experimental values.Comment: Further typos corrected, to appear in Phys. Rev.

    Large Possible retardation effects of quark confinement on the meson spectrum II

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    We present the results of a study of heavy-light-quark bound states in the context of the reduced Bethe-Salpeter equation with relativistic vector and scalar interactions. We find that satisfactory fits may also be obtained when the retarded effect of the quark-antiquark interaction is concerned.Comment: 11 pages, RevTex, to appear in PR

    Constraints from b→sγb \to s \gamma on gauge-mediated supersymmetry breaking models

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    We consider the branching ratio of b→sγb \to s\gamma in gauge mediated supersymmetry breaking theories. Useful bounds on the parameter space of these models are derived from the experimental bounds on b→sγb \to s\gamma. Constraints on masses of NLSP are presented as a function of tanβtan\beta and M/ΛM/\Lambda for μ0\mu0.Comment: 12 pages(Latex), 3 PS Figures (uuencoded, epsf.tex); minor modification in the introductory part of the tex

    Possible retardation effects of quark confinement on the meson spectrum

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    The reduced Bethe-Salpeter equation with scalar confinement and vector gluon exchange is applied to quark-antiquark bound states. The so called intrinsic flaw of Salpeter equation with static scalar confinement is investigated. The notorious problem of narrow level spacings is found to be remedied by taking into consideration the retardation effect of scalar confinement. Good fit for the mass spectrum of both heavy and light quarkomium states is then obtained.Comment: 14 pages in LaTex for

    Chiral Dynamics and Heavy Quark Symmetry in a Toy Field Theoretic Model

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    We study a solvable QCD--like toy theory, a generalization of the Nambu--Jona-Lasinio model, which implements chiral symmetries of light quarks and heavy quark symmetry. The chiral symmetric and chiral broken phases can be dynamically tuned. This implies a parity doubled heavy--light meson system, corresponding to a (0−,1−)(0^-,1^-) multiplet and a (0+,1+)(0^+,1^+) heavy spin multiplet. Consequently the mass difference of the two multiplets is given by a Goldberger--Treiman relation and gAg_A is found to be small. The Isgur--Wise function, ξ(w)\xi(w), the decay constant, fBf_B, and other observables are studied.Comment: 42 pages, SSCL-PP-243; Fermi-Pub-93/059-

    Negative T from a dynamical left-handed neutrino mass

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    We show how a dynamical Majorana mass for a fourth family left-handed neutrino can make a significant negative contribution to the electroweak correction parameter T without making a large contribution to S or U. We also comment on other possible contributions to T in the context of dynamical symmetry breaking.Comment: 8 pages, postscript, version to be published as Rapid Communications in PRD, PDF file is available at http://miteymac.physics.utoronto.ca/bh/papers/papers.htm
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