2,838 research outputs found

    Renormalizability of the massive Yang-Mills theory

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    It is shown that the massive Yang-Mills theory is on mass-shell renormalizable. Thus the Standard Model of electroweak interactions can be modified by removing terms with the scalar field from the Lagrangian in the unitary gauge. The resulting electroweak theory without the Higgs particle is on mass-shell renormalizable and unitary.Comment: 9 page

    Limits on Lorentz Violation from the Highest Energy Cosmic Rays

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    We place several new limits on Lorentz violating effects, which can modify particles' dispersion relations, by considering the highest energy cosmic rays observed. Since these are hadrons, this involves considering the partonic content of such cosmic rays. We get a number of bounds on differences in maximum propagation speeds, which are typically bounded at the 10^{-21} level, and on momentum dependent dispersion corrections of the form v = 1 +- p^2/Lambda^2, which typically bound Lambda > 10^{21} GeV, well above the Planck scale. For (CPT violating) dispersion correction of the form v = 1 + p/Lambda, the bounds are up to 15 orders of magnitude beyond the Planck scale.Comment: 24 pages, no figures. Added references, very slight changes. Version published in Physical Review

    Nonperturbative ghost dynamics in the maximal Abelian gauge

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    We construct the effective potential for the ghost condensate in the maximal Abelian gauge. This condensate is an order parameter for a global continuous symmetry, which is spontaneously broken since a nonvanishing value of lowers the vacuum energy. The associated Goldstone mode turns out to be unphysical.Comment: 16 pages. v2: version accepted for publication in JHE

    The Scientific and Social Activity of Professor N. N. Saltykov in Russia in 1894–1919

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    The scientific and social activity of Professor N. N. Saltykov in Russia in period 1894–1919 is presented

    Unknotting the polarized vacuum of quenched QED

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    A knot-theoretic explanation is given for the rationality of the quenched QED beta function. At the link level, the Ward identity entails cancellation of subdivergences generated by one term of the skein relation, which in turn implies cancellation of knots generated by the other term. In consequence, each bare three-loop diagram has a rational Laurent expansion in the Landau gauge, as is verified by explicit computation. Comparable simplification is found to occur in scalar electrodynamics, when computed in the Duffin-Kemmer-Petiau formalism.Comment: 11 pages, LaTe

    Dimensional Reduction applied to QCD at three loops

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    Dimensional Reduction is applied to \qcd{} in order to compute various renormalization constants in the \drbar{} scheme at higher orders in perturbation theory. In particular, the β\beta function and the anomalous dimension of the quark masses are derived to three-loop order. Special emphasis is put on the proper treatment of the so-called ϵ\epsilon-scalars and the additional couplings which have to be considered.Comment: 13 pages, minor changes, references adde

    The QCD Coupling Constant

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    This paper presents a summary of the current status of determinations of the strong coupling constant alpha_s. A detailed description of the definition, scale dependence and inherent theoretical ambiguities is given. The various physical processes that can be used to determine alpha_s are reviewed and attention is given to the uncertainties, both theoretical and experimental.Comment: 56 page

    Four-loop beta function and mass anomalous dimension in Dimensional Reduction

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    Within the framework of QCD we compute renormalization constants for the strong coupling and the quark masses to four-loop order. We apply the DR-bar scheme and put special emphasis on the additional couplings which have to be taken into account. This concerns the epsilon-scalar--quark Yukawa coupling as well as the vertex containing four epsilon-scalars. For a supersymmetric Yang Mills theory, we find, in contrast to a previous claim, that the evanescent Yukawa coupling equals the strong coupling constant through three loops as required by supersymmetry.Comment: 15 pages, fixed typo in Eq. (18

    The Q2Q^2 dependence of the measured asymmetry A1A_1: the test of the Bjorken sum rule

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    We analyse the proton and deutron data on spin dependent asymmetry A1(x,Q2)A_1(x,Q^2) supposing the DIS structure functions g1(x,Q2)g_1(x,Q^2) and F3(x,Q2)F_3(x,Q^2) have the similar Q2Q^2-dependence. As a result, we have obtained that Γ1pΓ1n=0.190±0.038\Gamma_1^p - \Gamma_1^n = 0.190 \pm 0.038 at Q2=10GeV2Q^2= 10 GeV^2 and Γ1pΓ1n=0.165±0.026\Gamma_1^p - \Gamma_1^n = 0.165 \pm 0.026 at Q2=3GeV2Q^2= 3 GeV^2, what is in the best agreement with the Bjorken sum rule predictions.Comment: LaTeX, 5 pages, no figures, to be published in JETP Letter

    An Alternative Method to Obtain the Quark Polarization of the Nucleon

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    An alternate method is described to extract the quark contribution to the spin of the nucleon directly from the first moment of the deuteron structure function, g1dg^d_1. It is obtained without recourse to the use of input on the nucleon wave function from hyperon decays involving the flavor symmetry parameters, F and D. The result for the quark polarization of the nucleon, ΔΣN,\Delta\Sigma_ N, is in good agreement with the values of the singlet axial current matrix element, a0a_0, obtained from recent next-to-leading order analyses of current proton, neutron and deuteron data.Comment: 7 pages, 1 figur
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