407 research outputs found

    Two dimensional QCD and abelian bosonization

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    A bosonized action, that reproduces the structure of the 't Hooft equation for QCD2QCD_2 in the large-NN limit, up to regularization dependent terms, is derived.Comment: paper revised, several signs and coefficients corrected. A comment on regularization dependence and several references adde

    Exact beta function from the holographic loop equation of large-N QCD_4

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    We construct and study a previously defined quantum holographic effective action whose critical equation implies the holographic loop equation of large-N QCD_4 for planar self-avoiding loops in a certain regularization scheme. We extract from the effective action the exact beta function in the given scheme. For the Wilsonean coupling constant the beta function is exacly one loop and the first coefficient agrees with its value in perturbation theory. For the canonical coupling constant the exact beta function has a NSVZ form and the first two coefficients agree with their value in perturbation theory.Comment: 42 pages, latex. The exponent of the Vandermonde determinant in the quantum effective action has been changed, because it has been employed a holomorphic rather than a hermitean resolution of identity in the functional integral. Beta function unchanged. New explanations and references added, typos correcte

    Phase structure of QCD for general number of flavors

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    We investigate and elucidate the phase structure of QCD for general number of flavors NFN_F with Wilson quarks, varying NFN_F from 2 up to 300. Based on numerical results combined with the result of the perturbation theory we propose the following picture: When NF17N_F \ge 17, there is only a trivial fixed point and therefore the theory in the continuum limit is trivial. On the other hand, when 16NF716 \ge N_F \ge 7, there is a non-trivial fixed point and therefore the theory is non-trivial with anomalous dimensions, however, without quark confinement. Theories which satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit exist only for NF6N_F \le 6. We also discuss the structure of the deconfining phase at finite temperatures for the small number of flavors such as NF=2N_F=2 and 3, through a systematic study of it for general number of flavors.Comment: LaTeX, 7 pages, 10 PS figures, Talk presented at LATTICE96(poster) and LATTICE96(finite temperature

    Finite Temperature QCD with Wilson Quarks: A Study with a Renormalization Group Improved Gauge Action

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    Finite temperature transition in lattice QCD with degenerate Wilson quarks is investigated on an Nt=4N_t=4 lattice, using a renormalization group improved gauge action. We find the following for the NF=2N_F=2 case: 1) The transition is smooth for a wide range of the quark mass. 2) The chiral transition is continuous. 3) The chiral condensation well satisfies a scaling relation with the critical exponents of the 3 dimensional O(4)O(4) spin model. For NF=3N_F=3, we find that the chiral transition is of first order.Comment: 4 pages (6 figures), Postscript file, Contribution to Lattice 95 proceeding

    The Light Quark Masses with the Wilson Quark Action using Chiral Ward Identities

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    We present results for the light quark masses for the Wilson quark action obtained with the PCAC relation for the one-link extended axial vector current in quenched QCD at β=5.96.5\beta=5.9-6.5. This method leads to a remarkable improvement of scaling behavior of the light quark masses compared to the conventional method. We obtain mˉl=3.87(37){\bar m}_l=3.87(37)MeV for the averaged up and down quark mass and mˉs=97(9){\bar m}_s=97(9)MeV for the strange quark mass in the {\barMS} scheme at μ=2\mu=2GeV.Comment: 3 pages, latex source-file, 2 figures as epsf-file, uses espcrc2.sty. Poster presented at Lattice 97: 15th International Symposium on Lattice Field Theory, Edinburgh, Scotland, 22-26 Jul 199

    Right-Wing Authoritarianism and Antipathy Toward Immigrants and Sexual Minorities in the Early Days of the Coronavirus Pandemic in Italy

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    Theory and research in social, evolutionary, and political psychology indicates that subjective feelings of threat and exposure to objectively threatening circumstances—including pandemic diseases—may contribute to increased affinities for political conservatism, right-wing authoritarianism, and prejudice against out-group members. We investigated these possibilities in the context of Italy, which was the first Western country to be severely affected by the spread of COVID-19. Early on in the pandemic, from March 3–8, 2020, we surveyed 757 Italian adults ranging in age from 18 to 78 years. Results revealed that antipathy toward immigrants and sexual minorities was predicted by (male) sex, COVID-19 anxiety, RWA, and political distrust. Furthermore, COVID-19 anxiety magnified the effect of RWA on disliking of immigrants and sexual minorities (but not obese or disabled people). Contrary to prediction, political trust failed to attenuate the effects of COVID-19 anxiety or RWA on out-group antipathy. Implications for the theories of right-wing authoritarianism and political ideology as motivated social cognition, as well as the state of contemporary Italian politics are discussed

    Finite-Temperature Phase Structure of Lattice QCD with Wilson Quark Action

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    The long-standing issue of the nature of the critical line of lattice QCD with the Wilson quark action at finite-temperatures, defined to be the line of vanishing pion screening mass, and its relation to the line of finite-temperature chiral tansition is examined. Analytical and numerical evidence are presented that the critical line forms a cusp at a finite gauge coupling, and the line of chiral transition runs past the tip of the cusp without touching the critical line. Implications on the continuum limit and the flavor dependence of chiral transition are discussed.Comment: 13 pages(4 figures), latex (epsf style-file needed), one sentence in abstract missed in transmission supplied and a few minor modifications in the text mad

    Finite-temperature chiral transitions in QCD with the Wilson quark action

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    We investigate the finite-temperature phase structure and the scaling of the chiral condensate in lattice QCD with two degenerate light quarks, using a renormalization group improved gauge action and the Wilson quark action. We obtain a phase diagram which is consistent with that from the parity-flavor breaking scenario. The scaling relation for the chiral condensate assuming the critical exponents and the scaling function of the three dimensional O(4) model is remarkably satisfied for a wide range of parameters. This indicates that the chiral transition in two flavor QCD is of second order in the continuum limit.Comment: LaTeX, 3 pages, 4 EPS figures, Talk presented at LATTICE97 (finite temperature

    Advances in the Determination of Quark Masses

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    Significant progress has been made in the determination of the light quark masses, using both lattice QCD and sum rule methods, in the last year. We discuss the different methods and review the status of current results. Finally, we review the calculations of bottom and charm quark masses.Comment: 14 pages. Package submitted in uufiles format: unpack and latex paper.tex. Plenary talk presented at LATTICE97. This version fixes typos in the proceedings version and includes additional dat

    TUNING TO N=2N=2 SUPERSYMMETRY IN THE SU(2) ADJOINT HIGGS-YUKAWA MODEL

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    The N=2N=2 supersymmetric continuum limit is investigated in the SU(2) adjoint Higgs-Yukawa model using lattice perturbation theory. In the one-loop renormalization group equations a non-trivial infrared fixed point of coupling ratios is found. The phase structure at weak couplings is determined by a numerical study of the one-loop effective potential.Comment: 32 pages, latex, 7 figures
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