5,222 research outputs found
Results from pQCD for A+A collisions at RHIC & LHC energies
This talk will discuss how to compute initial quantites in heavy ion
collisions at RHIC (200 AGeV) and at LHC (5500 AGeV) using perturbative QCD
(pQCD) by including the next-to-leading order (NLO) corrections and a dynamical
determination of the dominant physical scale. The initial numbers are converted
into final ones by assuming kinetic thermalization and adiabatic expansion.Comment: 4 pages, 2 eps-figures, to appear in Proceedings of CIPANP2000, 7th
Conference on the Intersections of Particle and Nuclear Physics, May 22-28,
2000, Quebec Cit
Light Composite Higgs from Higher Representations versus Electroweak Precision Measurements -- Predictions for LHC
We investigate theories in which the technifermions in higher dimensional
representations of the technicolor gauge group dynamically break the
electroweak symmetry of the standard model. For the two-index symmetric
representation of the gauge group the lowest number of techniflavors needed to
render the underlying gauge theory quasi conformal is two. We confront the
models with the recent electroweak precision measurements and demonstrate that
the two technicolor theory is a valid candidate for a dynamical breaking of the
electroweak symmetry. The electroweak precision measurements provide useful
constraints on the relative mass splitting of the new leptons needed to cure
the Witten anomaly. In the case of a fourth family of leptons with ordinary
lepton hypercharge the new heavy neutrino can be a natural candidate of cold
dark matter. We also propose theories in which the critical number of flavors
needed to enter the conformal window is higher than the one with fermions in
the two-index symmetric representation, but lower than in the walking
technicolor theories with fermions only in the fundamental representation of
the gauge group. Due to the near conformal/chiral phase transition, we show
that the composite Higgs is very light compared to the intrinsic scale of the
technicolor theory. For the two technicolor theory we predict the composite
Higgs mass not to exceed 150 GeV.Comment: RevTex, 53 pages, 7 figures and two table
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