8,158 research outputs found
Mooses, Topology and Higgs
New theories of electroweak symmetry breaking have recently been constructed
that stabilize the weak scale and do not rely upon supersymmetry. In these
theories the Higgs boson is a weakly coupled pseudo-Goldstone boson. In this
note we study the class of theories that can be described by theory spaces and
show that the fundamental group of theory space describes all the relevant
classical physics in the low energy theory. The relationship between the low
energy physics and the topological properties of theory space allow a
systematic method for constructing theory spaces that give any desired low
energy particle content and potential. This provides us with tools for
analyzing and constructing new theories of electroweak symmetry breaking.Comment: 16 pages, 11 figure
Phenomenology of Electroweak Symmetry Breaking from Theory Space
Recently, a new class of realistic models for electroweak symmetry breaking
have been constructed, without supersymmetry. These theories have naturally
light Higgs bosons and perturbative new physics at the TeV scale. We describe
these models in detail, and show that electroweak symmetry breaking can be
triggered by a large top quark Yukawa coupling. A rich spectrum of particles is
predicted, with a pair of light Higgs doublets accompanied by new light weak
triplet and singlet scalars. The lightest of these new scalars is charged under
a geometric discrete symmetry and is therefore stable, providing a new
candidate for WIMP dark matter. At TeV energies, a plethora of new heavy
scalars, gauge bosons and fermions are revealed, with distinctive quantum
numbers and decay modes.Comment: 22 pages, latex, 6 figures. Numerical results corrected,
clarifications added, conclusions unchange
Brane Universe and Multigravity: Modification of gravity at large and small distances
We consider a modification of gravity at large distances in a Brane Universe
which was discussed recently. In these models the modification of gravity at
large distances is ultimately connected to existence of negative tension
brane(s) and exponentially small tunneling factor. We discuss a general model
which interpolates between Bi-gravity model and GRS model. We also discuss the
possible mechanism of stabilization for negative tension branes in AdS
background. Finally we show that extra degrees of freedom of massive gravitons
do not lead to disastrous contradiction with General Relativity if the
stabilization condition is
implemented.Comment: 12 pages, 4 eps figures, LaTe
The Minimal Moose for a Little Higgs
Recently a new class of theories of electroweak symmetry breaking have been
constructed. These models, based on deconstruction and the physics of theory
space, provide the first alternative to weak-scale supersymmetry with naturally
light Higgs fields and perturbative new physics at the TeV scale. The Higgs is
light because it is a pseudo-Goldstone boson, and the quadratically divergent
contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of
the {\em same} statistics. In this paper we present the minimal theory space
model of electroweak symmetry breaking, with two sites and four link fields,
and the minimal set of fermions. There are very few parameters and degrees of
freedom beyond the Standard Model. Below a TeV, we have the Standard Model with
two light Higgs doublets, and an additional complex scalar weak triplet and
singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic
divergences in the Higgs mass are revealed. The entire Higgs potential needed
for electroweak symmetry breaking--the quartic couplings as well as the
familiar negative mass squared--can be generated by the top Yukawa coupling,
providing a novel link between the physics of flavor and electroweak symmetry
breaking.Comment: 15 pages. References added. Included clarifying comments on the
origin of quartic couplings, and on power-counting. More elegant model for
generating Higgs potential from top Yukawa coupling presente
The Higgs puzzle: experiment and theory
The present experimental and theoretical knowledge of the physics of
electroweak symmetry breaking is reviewed. Data still favor a light Higgs
boson, of a kind that can be comfortably accommodated in the Standard Model or
in its Minimal Supersymmetric extension, but exhibit a non-trivial structure
that leaves some open questions. The available experimental information may
still be reconciled with the absence of a light Higgs boson, but the price to
pay looks excessive. Recent theoretical ideas, linking the weak scale with the
size of possible extra spatial dimensions, are briefly mentioned. It is
stressed once more that experiments at high-energy colliders, such as the
Tevatron and the LHC, are the crucial tool for eventually solving the Higgs
puzzle.Comment: 18 pages, 13 figures, invited talk at the 20th International
Symposium on Lepton and Photon Interactions at High Energies (Lepton Photon
01), Rome, Italy, 23-28 July 200
Infinitely Large New Dimensions
We construct intersecting brane configurations in Anti-de-Sitter space
localizing gravity to the intersection region, with any number of extra
dimensions. This allows us to construct two kinds of theories with infinitely
large new dimensions, TeV scale quantum gravity and sub-millimeter deviations
from Newton's Law. The effective 4D Planck scale is determined in
terms of the fundamental Planck scale and the radius of curvature
via the familiar relation ; acts as an
effective radius of compactification for gravity on the intersection. Taking
TeV and sub-mm reproduces the phenomenology of theories
with large extra dimensions. Alternately, taking ,
and placing our 3-brane a distance away from the
intersection gives us a theory with an exponential determination of the
Weak/Planck hierarchy.Comment: 4 pages, revtex, no figure
Black Holes at Future Colliders and Beyond
One of the most dramatic consequences of low-scale (~1 TeV) quantum gravity
is copious production of mini black holes at future accelerators and in
ultra-high-energy cosmic ray interactions. Hawking radiation of these black
holes is constrained mainly to our (3+1)-dimensional world and results in rich
phenomenology. We discuss tests of Wien's law of Hawking radiation, which is a
sensitive probe of the dimensionality of extra space, as well as an exciting
possibility of finding new physics in the decays of black holes.Comment: 8 pages, 4 figures, uses moriond02.sty, included. Talk given at the
XXXVIIth Rencontres de Moriond "QCD and Hadronic interactions," Les Arcs,
March 16-23, 200
Constraints on the thermal evolution of Venus inferred from Magellan data
The impact craters with diameters from 1.5 to 280 km compiled from Magellan observations indicate that the crater population on Venus has a completely spatially random distribution and the size/density distribution of craters with diameters greater than or equal to 35 km is consistent with a 'production' population with an age of 500 plus or minus 250 m.y. The similarity in size distribution from area to area indicates that the crater distribution is independent of crater size. Also, the forms of the modified craters are virtually identical to those of the pristine craters. These observations imply that Venus reset its cratering record by global resurfacing 500 m.y. ago, and resurfacing declined relatively fast. The fact that less than 40 percent of all craters have been modified and that the few volcanically embayed craters are located on localized tectonic regions indicate that only minor and localized volcanism and tectonism have occurred since the latest vigorous resurfacing event approximately 500 m.y. ago and the interior of Venus has been solid and possibly colder than Earth's. This is because the high-temperature lithosphere of Venus would facilitate upward ascending of mantle plumes and result in extensive volcanism if the venusian upper mantle were as hot as or hotter than Earth's. Therefore, the present surface morphology of Venus may provide useful constraints on the pattern of that vigorous convection, and possibly on the thermal state of the venusian mantle. We examine this possibility through numerical calculations of three-dimensional thermal convection models in a spherical shell with temperature- and pressure-dependent Newtonian viscosity, temperature-dependent thermal diffusivity, pressure-dependent thermal expansion coefficient, and time-dependent internal heat production rate solar magnitude
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