5,169 research outputs found
The Higgs portal and an unified model for dark energy and dark matter
We examine a scenario where the Higgs boson is coupled to an additional
singlet scalar field which we identify with a quintessence field. We show that
this results in an unified picture of dark matter and dark energy, where dark
energy is the zero-mode classical field rolling the usual quintessence
potential and the dark matter candidate is the quantum excitation (particle) of
the field, which is produced in the universe due to its coupling to the Higgs
boson.Comment: 5 pages, no figures. New references and acknowledgment adde
A Comparison of Predictions for SM Higgs Boson Production at the LHC
This paper describes a comparison of most of the available predictions for
the cross section and transverse momentum distribution for a 125 GeV mass Higgs
at the LHC, including those from the PYTHIA and HERWIG parton shower Monte
Carlos and from four resummation calculations.Comment: 7 pages, submitted to proceedings of the Workshop on Physics at TeV
Colliders, Les Houches 200
Yukawa Coupling Unification in Supersymmetric Models
We present an updated assessment of the viability of t-b-tau Yukawa coupling
unification in supersymmetric models. For the superpotential Higgs mass
parameter mu>0, we find unification to less than 1% is possible, but only for
GUT scale scalar mass parameter m_{16}~8-20 TeV, and small values of gaugino
mass m_{1/2}<400 GeV. Such models require that a GUT scale mass splitting
exists amongst Higgs scalars with m_{H_u}^2<m_{H_d}^2. Viable solutions lead to
a radiatively generated inverted scalar mass hierarchy, with third generation
and Higgs scalars being lighter than other sfermions. These models have very
heavy sfermions, so that unwanted flavor changing and CP violating SUSY
processes are suppressed, but may suffer from some fine-tuning requirements.
While the generated spectra satisfy b->s gamma and (g-2)_mu constraints, there
exists tension with the dark matter relic density unless m_{16}<3 TeV. These
models offer prospects for a SUSY discovery at the Fermilab Tevatron collider
via the search for chargino_1 neutralino_2 -> 3 leptons events, or via gluino
pair production. If mu<0, Yukawa coupling unification to less than 5% can occur
for m_{16} and m_{1/2}>1-2 TeV. Consistency of negative mu Yukawa unified
models with b->s gamma, (g-2)_mu, and relic density all imply very large values
of m_{1/2} typically greater than about 2.5 TeV, in which case direct detection
of sparticles may be a challenge even at the LHC.Comment: 38 pages, 15 figures. Fig.15 changed, some references were added. A
copy of the paper with better resolution figures can be found at
http://www.hep.fsu.edu/~balazs/Physics/Papers/2003
Viable models with non-universal gaugino mediated supersymmetry breaking
Recently, extra dimensional SUSY GUT models have been proposed in which
compactification of the extra dimension(s) leads to a breakdown of the gauge
symmetry and/or supersymmetry. We examine a particular class of
higher-dimensional models exhibiting supersymmetry and SU(5) or SO(10) GUT
symmetry. SUSY breaking occurs on a hidden brane, and is communicated to the
visible brane via gaugino mediation. Non-universal gaugino masses are developed
at the compactification scale as a consequence of a restricted gauge symmetry
on the hidden brane. In this case, the compactification scale is at or slightly
below the GUT scale. We examine the parameter space of such models where
gaugino masses are related due to a Pati-Salam symmetry on the hidden brane. We
find limited but significant regions of model parameter space where a viable
spectra of SUSY matter is generated. Our results are extended to the more
general case of three independent gaugino masses; here we find that large
parameter space regions open up for large values of the U(1) gaugino mass M_1.
We also find the relic density of neutralinos for these models to be generally
below expectations from cosmological observations, thus leaving room for hidden
sector states to make up the bulk of cold dark matter. Finally, we evaluate the
branching fraction BF(b -> s gamma) and muon anomalous magnetic moment a_\mu.Comment: 21 pages, 9 figure
Correspondence in Quasiperiodic and Chaotic Maps: Quantization via the von Neumann Equation
A generalized approach to the quantization of a large class of maps on a
torus, i.e. quantization via the von Neumann Equation, is described and a
number of issues related to the quantization of model systems are discussed.
The approach yields well behaved mixed quantum states for tori for which the
corresponding Schrodinger equation has no solutions, as well as an extended
spectrum for tori where the Schrodinger equation can be solved.
Quantum-classical correspondence is demonstrated for the class of mappings
considered, with the Wigner-Weyl density going to the correct
classical limit. An application to the cat map yields, in a direct manner,
nonchaotic quantum dynamics, plus the exact chaotic classical propagator in the
correspondence limit.Comment: 36 pages, RevTex preprint forma
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