1,870 research outputs found
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 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 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 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 and electroweak parameters can be naturally suppressed
by a custodial symmetry, while the 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
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