65,987 research outputs found
Nature of Decoupling in the Mixed Phase of Extremely Type-II Layered Superconductors
The uniformly frustrated layered XY model is analyzed in its Villain form. A
decouple pancake vortex liquid phase is identified. It is bounded by both
first-order and second-order decoupling lines in the magnetic field versus
temperature plane. These transitions, respectively, can account for the
flux-lattice melting and for the flux-lattice depinning observed in the mixed
phase of clean high-temperature superconductors.Comment: 11 pages of PLAIN TeX, 1 postscript figure, published version, many
change
Optimum pinning of the vortex lattice in extremely type-II layered superconductors
The two-dimensional (2D) vortex lattice in the extreme type-II limit is
studied by Monte Carlo simulation of the corresponding 2D Coulomb gas, with
identical pins placed at sites coinciding with the zero-temperature triangular
vortex lattice. At weak pinning we find evidence for 2D melting into an
intermediate hexatic phase. The strong pinning regime shows a
Kosterlitz-Thouless transition, driven by interstitial vortex/anti-vortex
excitations. A stack of such identical layers with a weak Josephson coupling
models a layered superconductor with a triangular arrangement of columnar pins
at the matching field. A partial duality analysis finds that layer decoupling
of the flux-line lattice does not occur at weak pinning for temperatures below
2D melting.Comment: 5 pgs., 4 figs. To appear in PRB. Added size study of hexatic phas
Left-right asymmetries and exotic vector-boson discovery in lepton-lepton colliders
By considering left-right (L-R) asymmetries we study the capabilities of
lepton colliders in searching for new exotic vector bosons. Specifically we
study the effect of a doubly charged bilepton boson and an extra neutral vector
boson appearing in a 3-3-1 model on the L-R asymmetries for the processes
, and and
show that these asymmetries are very sensitive to these new contributions and
that they are in fact powerful tools for discovery this sort of vector bosons.Comment: RevTeX, 22 pages, 12 eps figure
A supersymmetric 3-3-1 model
We build the complete supersymmetric version of a 3-3-1 gauge model using the
superfield formalism. We point out that a discrete symmetry, similar to the
R-symmetry in the minimal supersymmetric standard model, is possible to be
defined in this model. Hence we have both R-conserving and R-violating
possibilities. Analysis of the mass spectrum of the neutral real scalar fields
shown that in this model the lightest scalar Higgs has a mass upper limit, and
at the tree level it is 124.5 GeV for a given illustrative set of parameters.Comment: RevTex, extended and revised version, 20 pages, one eps figur
Optimal design of pipes in series: An explicit approximation
This paper introduces a new methodology for the optimum design of pipes in series, named Optimum Hydraulic Grade Line (OHGL). This methodology is explicit and is based on the knowledge of the series topology and the geometrical distribution of water demands on nodes, i.e. the way in which the pipe in series delivers water mass as function of the distance from the entrance. OHGL consists in the pre-determination of that hydraulic grade line which gives the minimum construction cost, in an explicit way. Once this line has been established, calculation of the pipe’s continuous diameters is direct; after a round up to commercial diameters is developed. To validate the proposed methodology, several pipes in series were designed both using GA and OHGL. Four hundred series were used in total, each with different topological characteristics and demands. Keywords: Pipe in series, optimum design, genetic algorithms, optimum hydraulic grade line
Anomalous Nernst Effect in the Vortex-Liquid Phase of High-Temperature Superconductors by Layer Decoupling
Linear diamagnetism is predicted in the vortex-liquid phase of layered
superconductors at temperatures just below the mean-field phase transition on
the basis of a high-temperature analysis of the corresponding frustrated XY
model. The diamagnetic susceptibility, and the Nernst signal by implication, is
found to vanish with temperature as (T_c0 - T)^3 in the vicinity of the
meanfield transition at T_c0. Quantitative agreement with recent experimental
observations of a diamagnetic signal in the vortex-liquid phase of
high-temperature superconductors is obtained.Comment: 8 pages, 3 figure
Supersymmetric 3-3-1 model with right-handed neutrinos
We consider the supersymmetric extension of the 3-3-1 model with right-handed
neutrinos. We study the mass spectra in the scalar and pseudoscalar sectors,
and for a given set of the input parameters, we find that the lightest scalar
in the model has a mass of 130 GeV and the lightest pseudoscalar has mass of 5
GeV. However, this pseudoscalar decouples from the at high energy scales
since it is almost a singlet under .Comment: Revtex4, 16 pages, no figure
- …