1,121 research outputs found

    Gauge invariant formulation of strong WW scattering

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    Models of strong WWWW scattering in the ss-wave can be represented in a gauge invariant fashion by defining an effective scalar propagator that represents the strong scattering dynamics. The \sigma(qq \ra qqWW) signal may then be computed in U-gauge from the complete set of tree amplitudes, just as in the standard model, without using the effective WW approximation (EWA). The U-gauge ``transcription'' has a wider domain of validity than the EWA, and it provides complete distributions for the final state quanta, including experimentally important jet distributions that cannot be obtained from the EWA. Starting from the usual formulation in terms of unphysical Goldstone boson scattering amplitudes, the U-gauge transcription is verified by using BRS invariance to construct the complete set of gauge and Goldstone boson amplitudes in RξR_{\xi} gauge.Comment: single LaTeX file, no figures, 12 page

    Strong WW scattering in unitary gauge

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    A method to embed models of strong WWWW scattering in unitary gauge amplitudes is presented that eliminates the need for the effective WW approximation (EWA) in the computation of cross sections at high energy colliders.The cross sections obtained from the U-gauge amplitudes include the distributions of the final state fermions in ffffWWff \rightarrow ffWW, which cannot be obtained from the EWA. Since the U-gauge method preserves the interference of the signal and the gauge sector background amplitudes, which is neglected in the EWA, it is more accurate, especially if the latter is comparable to or bigger than the signal, as occurs for instance at small angles because of Coulomb singularities. The method is illustrated for on-shell W+W+W+W+W^+W^+ \rightarrow W^+W^+ scattering and for qqqqW+W+qq \rightarrow qqW^+W^+.Comment: 14 pages, Latex with 2 epsf-embedded postscript figure

    Inelastic Channels in the Electroweak Symmetry-Breaking Sector

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    It has been argued that if light Higgs bosons do not exist then the self--interactions of WW's become strong in the TeV region and can be observed in longitudinal WWWW scattering. We present a model with many inelastic channels in the WWWW scattering process, corresponding to the creation of heavy fermion pairs. The presence of these heavy fermions affects the elastic scattering of WW's by propagating in loops, greatly reducing the amplitudes in some charge channels. Consequently, the symmetry--breaking sector cannot be fully explored by using, for example, the W+W+W^+W^+ mode alone; all WWWWWW \rightarrow WW scattering modes must be measured.}Comment: 10 pages, phyzzx, JHU-TIPAC-92001

    Reply to Comment on "Chiral suppression of scalar glueball decay"

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    Reply to the comment of Chao, He, and Ma

    Chiral Suppression of Scalar Glueball Decay

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    Because glueballs are SU(3)_{Flavor} singlets, they are expected to couple equally to u,d, and s quarks, so that equal coupling strengths to \pi^+\pi^- and K^+K^- are predicted. However, we show that chiral symmetry implies the scalar glueball amplitude for G_0 \to \qbq is proportional to the quark mass, so that mixing with \sbs mesons is enhanced and decays to K^+K^- are favored over \pi^+\pi^-. Together with evidence from lattice calculations and from experiment, this supports the hypothesis that f_0(1710) is the ground state scalar glueball.Comment: 9 pages; This revision reconciles posting (approximately) with published version. Posting contains figures that are omitted in the publicatio

    The No-Higgs Signal: Strong WW Scattering at the LHC

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    Strong WW scattering at the LHC is discussed as a manifestation of electroweak symmetry breaking in the absence of a light Higgs boson. The general framework of the Higgs mechanism -- with or without a Higgs boson -- is reviewed, and unitarity is shown to fix the scale of strong WW scattering. Strong WW scattering is also shown to be a possible outcome of five-dimensional models, which do not employ the usual Higgs mechanism at the TeV scale. Precision electroweak constraints are briefly discussed. Illustrative LHC signals are reviewed for models with QCD-like dynamics, stressing the complementarity of the W^{\pm}Z and like-charge W^+W^+ + W^-W^- channels.Comment: 16 pages, talk presented at Physics at LHC, July 13 - 17, 2004, Vienna, Austria, to be published in the proceeding

    The Direct Limit on the Higgs Mass and the SM Fit

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    Because of two 3σ3\sigma anomalies, the Standard Model (SM) fit of the precision electroweak data has a poor confidence level, CL=0.02CL= 0.02. Since both anomalies involve challenging systematic issues, it might appear that the SM could still be valid if the anomalies resulted from underestimated systematic error. Indeed the CLCL of the global fit could then increase to 0.71, but that fit predicts a small Higgs boson mass, mH=45m_H=45 GeV, that is inconsistent at 95% CL with the lower limit, mH>114m_H>114 GeV, established by direct searches. The data then favor new physics if the anomalous measurements are both excluded or both retained, and the Higgs boson mass cannot be predicted until the new physics is understood. The validity of the SM could however be maintained by a propitious combination of statistical fluctuation and systematic error. The current data do not allow a definitive conclusion.Comment: 12 pages, 4 figures, presented at the Workshop on Electroweak Precision Data and the Higgs Mass, DESY-Zeuthen, February 28 - March 1, 2003; typos in table 3 corrected, discussion of products of CL's generalized; kinder, gentler abstrac
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