114 research outputs found
Quantum Hall Ferrimagnetism in lateral quantum dot molecules
We demonstrate the existance of ferrimagnetic and ferromagnetic phases in a
spin phase diagram of coupled lateral quantum dot molecules in the quantum Hall
regime. The spin phase diagram is determined from Hartree-Fock Configuration
Interaction method as a function of electron numbers N, magnetic field B,
Zeeman energy, and tunneling barrier height. The quantum Hall ferrimagnetic
phase corresponds to spatially imbalanced spin droplets resulting from strong
inter-dot coupling of identical dots. The quantum Hall ferromagnetic phases
correspond to ferromagnetic coupling of spin polarization at filling factors
between and .Comment: 4 pages, 4 figure
Some house, lawn, and field ants of eastern Kansas
LD2668 .T4 1941 M33Master of Scienc
HERBVI - a program for simulation of baryon- and lepton- number violating processes
We describe a Monte Carlo event generator for the simulation of baryon- and
lepton-number violating processes at supercolliders. The package, {\HERBVI}, is
designed as a hard-process generator interfacing to the general hadronic event
simulation program {\HW}. In view of the very high multiplicity of gauge bosons
expected in such processes, particular attention is paid to the efficient
generation of multiparticle phase space. The program also takes account of the
expected colour structure of baryon-number violating vertices, which has
important implications for the hadronization of the final state.Comment: 19 pages, standard LaTeX, no figure
Solvability, Consistency and the Renormalization Group in Large- Models of Hadrons
We establish the following fundamentals about Lagrangian models of
meson-baryon interactions in the large- limit: 1. Calculating the
leading-order contribution to -meson/-baryon Green's functions in the
expansion involves summing an infinite class of divergent Feynman
diagrams. So long as the bare Lagrangian properly obeys all large-
selection rules, this all-loops resummation is accomplished exactly by solving
coupled classical field equations with a short-distance cutoff. 2. The only
effect of the resummation is to renormalize the bare Yukawa couplings, baryon
masses and hyperfine baryon mass splittings of the model. 3. In the process,
the large- renormalization group flow of these bare parameters is
completely determined. We conjecture that variants of the Skyrme model emerge
as UV fixed points of such flows.Comment: (LaTeX file with accompanying figures
Soliton quantization and internal symmetry
We apply the method of collective coordinate quantization to a model of
solitons in two spacetime dimensions with a global symmetry. In
particular we consider the dynamics of the charged states associated with
rotational excitations of the soliton in the internal space and their
interactions with the quanta of the background field (mesons). By solving a
system of coupled saddle-point equations we effectively sum all tree-graphs
contributing to the one-point Green's function of the meson field in the
background of a rotating soliton. We find that the resulting one-point function
evaluated between soliton states of definite charge exhibits a pole on
the meson mass shell and we extract the corresponding S-matrix element for the
decay of an excited state via the emission of a single meson using the standard
LSZ reduction formula. This S-matrix element has a natural interpretation in
terms of an effective Lagrangian for the charged soliton states with an
explicit Yukawa coupling to the meson field. We calculate the leading-order
semi-classical decay width of the excited soliton states discuss the
consequences of these results for the hadronic decay of the resonance
in the Skyrme model.Comment: 23 pages, LA-UR-93-299
Solution of the infinite range t-J model
The t-J model with constant t and J between any pair of sites is studied by
exploiting the symmetry of the Hamiltonian with respect to site permutations.
For a given number of electrons and a given total spin the exchange term simply
yields an additive constant. Therefore the real problem is to diagonalize the
"t- model", or equivalently the infinite U Hubbard Hamiltonian. Using
extensively the properties of the permutation group, we are able to find
explicitly both the energy eigenvalues and eigenstates, labeled according to
spin quantum numbers and Young diagrams. As a corollary we also obtain the
degenerate ground states of the finite Hubbard model with infinite range
hopping -t>0.Comment: 15 pages, 2 figure
Skyrmion Quantization and the Decay of the Delta
We present the complete solution to the so-called ``Yukawa problem'' of the
Skyrme model. This refers to the perceived difficulty of reproducing---purely
from soliton physics---the usual pseudovector pion-nucleon coupling, echoed by
pion coupling to the higher spin/isospin baryons in a manner fixed by large- group theory. The solution involves
surprisingly elegant interplay between the classical and quantum properties of
a new configuration, the ``new improved skyrmion''. This is the near-hedgehog
obtained by minimizing the usual skyrmion mass functional augmented by an
all-important isorotational kinetic term. The numerics are pleasing: a
decay width within a few MeV of its measured value, and furthermore, the
higher-spin baryons with widths so large ()
that these undesirable large- artifacts effectively drop out of the
spectrum, and pose no phenomenological problem. Beyond these specific results,
we ground the Skyrme model in the Feynman Path Integral, and set up a
transparent collective coordinate formalism that makes maximal use of the
expansion. This approach elucidates the connection between skyrmions on
the one hand, and Feynman diagrams in an effective field theory on the other.Comment: This TeX file inputs the macropackage harvmac.tex . Choose the ``b''
(big) option or equations will overrun
Routing of Network Traffic on a Per-Application Basis
Wireless applications in certain domains, e.g., automotive, Internet-of-Things (IoT), etc., consume substantial amounts of bandwidth. A user accustomed to data consumption on a mobile device may be surprised to find the substantially larger amounts of data consumed via telemetry by wireless devices and sensors on their automobile. Reciprocally, a car manufacturer may not want a customer to pay for telemetry. This disclosure describes techniques to route network traffic to specific network interfaces on a per-application basis. The techniques can be implemented in a device operating system, and provide mechanisms for users and original equipment manufacturers (OEMs) to separate data costs for usage of various applications, thereby enabling a robust, secure, and connected experience
Around the world in 17 days ? hemispheric-scale transport of forest fire smoke from Russia in May 2003
International audienceIn May 2003, severe forest fires in southeast Russia resulted in smoke plumes extending widely across the Northern Hemisphere. This study combines satellite data from a variety of platforms (Moderate Resolution Imaging Spectroradiometer (MODIS), Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Earth Probe Total Ozone Mapping Spectrometer (TOMS) and Global Ozone Monitoring Experiment (GOME)) and vertical aerosol profiles derived with Raman lidar measurements with results from a Lagrangian particle dispersion model to understand the transport processes that led to the large haze plumes observed over North America and Europe. The satellite images provided a unique opportunity for validating model simulations of tropospheric transport on a truly hemispheric scale. Transport of the smoke occurred in two directions: Smoke travelling northwestwards towards Scandinavia was lifted over the Urals and arrived over the Norwegian Sea. Smoke travelling eastwards to the Okhotsk Sea was also lifted, it then crossed the Bering Sea to Alaska from where it proceeded to Canada and was later even observed over Scandinavia and Eastern Europe on its way back to Russia. This is perhaps the first time that air pollution was observed to circle the entire globe. The total transport time was about 17 days. We compared transport model simulations using meteorological analysis data from both the European Centre for Medium-Range Weather Forecast (ECMWF) and the National Center for Environmental Prediction (NCEP) in order to find out how well this event could be simulated using these two datasets. Although differences between the two simulations are found on small scales, both agree remarkably well with each other and with the observations on large scales. On the basis of the available observations, it cannot be decided which simulation was more realistic
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Evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 Eyjafjallajökull eruption using lidar observations and NAME simulations
The Eyjafjallajökull volcano in Iceland erupted explosively on 14 April 2010, emitting a plume of ash into the atmosphere. The ash was transported from Iceland toward Europe where mostly cloud-free skies allowed ground-based lidars at Chilbolton in England and Leipzig in Germany to estimate the mass concentration in the ash cloud as it passed overhead. The UK Met Office's Numerical Atmospheric-dispersion Modeling Environment (NAME) has been used to simulate the evolution of the ash cloud from the Eyjafjallajökull volcano during the initial phase of the ash emissions, 14–16 April 2010. NAME captures the timing and sloped structure of the ash layer observed over Leipzig, close to the central axis of the ash cloud. Relatively small errors in the ash cloud position, probably caused by the cumulative effect of errors in the driving meteorology en route, result in a timing error at distances far from the central axis of the ash cloud. Taking the timing error into account, NAME is able to capture the sloped ash layer over the UK. Comparison of the lidar observations and NAME simulations has allowed an estimation of the plume height time series to be made. It is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range. Quantitative comparison with the mass concentrations at Leipzig and Chilbolton suggest that around 3% of the total emitted mass is transported as far as these sites by small (<100 μm diameter) ash particles
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