Few exact results on gauge symmetry factorizability on intervals

We study the gauge symmetry factorizability by boundary conditions on intervals of any dimensions. With Dirichlet-Neumann BCs, the Kaluza-Klein decomposition in five-dimension for arbitrary gauge group can always be factorized into that for separate subsets of at most two gauge symmetries, and so is completely solvable. Accordingly, we formulate a limit theorem on gauge symmetry factorizability on intervals to recapitulate this remarkable feature of five-dimension case. In higher-dimensional space-time, an interesting chained mixing of gauge symmetries by Dirichlet-Neumann BCs is explicitly constructed. The systematic decomposition picture obtained in this work constitutes the initial step towards determining the general symmetry breaking scheme by boundary conditions.Comment: 34 pages, V3 considerable extension: gauge symmetry factorizability in arbitrary dimensions presented, statements on symmetry breakings softened. Dedicated to the memory of Prof. Henri van Regemorte

Triviality and the Precision Bound on the Higgs Mass

The triviality of the scalar sector of the standard one-doublet Higgs model implies that this model is only an effective low-energy theory valid below some cut-off scale Lambda. For a heavy higgs this scale must be relatively low (10 TeV or less). Additional interactions coming from the underlying theory, and suppressed by the scale Lambda, give rise to model-dependent corrections to precisely measured electroweak quantities. Dimension six operators arising from the underlying physics naturally contribute to the S and T parameters, and their effects should be included in a global fit to the precision data that determines any limit on the Higgs mass. Using dimensional analysis, we estimate the expected size of these corrections in a custodially-symmetric strongly-interacting underlying theory. Taking these operators' coefficients to be of natural size gives sufficiently large contributions to the T parameter to reconcile Higgs masses as large as 400-500 GeV with the precision data.Comment: 9 pages, 3 epsf figures include

New Strong Interactons at the Tevatron ?

Recent results from CDF indicate that the inclusive cross section for jets with $E_T > 200$ GeV is significantly higher than that predicted by QCD. We describe here a simple flavor-universal variant of the ``coloron" model of Hill and Parke that can accommodate such a jet excess, and which is not in contradiction with other experimental data. As such, the model serves as a useful baseline with which to compare both the data and other models proposed to describe the jet excess. An interesting theoretical feature of the model is that if the global chiral symmetries of the quarks remain unbroken in the confining phase of the coloron interaction, it realizes the possibility that the ordinary quarks are composite particles.Comment: added $1/Lambda^4$ contributions to scattering cross-sections; 10 pages, LaTeX, includes 1 figure. Full postscript version at http://smyrd.bu.edu/htfigs/htfigs.htm

A New Model of Topcolor-Assisted Technicolor

I present a model of topcolor-assisted technicolor that can have topcolor breaking of the desired pattern, hard masses for all quarks and leptons, mixing among the heavy and light generations, and explicit breaking of all technifermion chiral symmetries except electroweak $SU(2) \otimes$U(1). These positive features depend on the outcome of vacuum alignment. The main flaw in this model is tau-lepton condensation.Comment: 9 pages, TeX, uses harvmac.te

Effects of Fermion Localization in Higgsless Theories and Electroweak Constraints

Extra-dimensional Higgsless models with electroweak symmetry breaking through boundary conditions generically have difficulties with electroweak precision constraints, when the fermions are localized to the ``branes'' in the fifth dimension. In this paper we show that these constraints can be relaxed by allowing the light fermions to have a finite extent into the bulk of the fifth dimension. The $T$ and $U$ electroweak parameters can be naturally suppressed by a custodial symmetry, while the $S$ parameter can be made to vanish through a cancellation, if the leakage into the bulk of the light gauge fields and the light left-handed fermion fields are of the same size. This cancellation is possible while allowing realistic values for the first two generations of fermion masses, although special treatment is probably required for the top quark. We present this idea here in the context of a specific continuum theory-space model; however, it can be applied to any five-dimensional Higgsless model, either with a flat or a warped background.Comment: 10 pages, JHEP format, comments and reference to related paper adde