11,635 research outputs found
The chemical potential for the inhomogeneous electron liquid in terms of its kinetic and potential parts with special consideration of the surface pote ntial step and BCS-BEC crossover
The chemical potential of a many-body system is valuable since it
carries fingerprints of phase changes. Here, we summarize results for for
a thre e-dimensional electron liquid in terms of average kinetic and potential
energie s per particle. The difference between and the energy per
particle is fou nd to be exactly the electrostatic potential step at the
surface. We also prese nt calculations for an integrable one-dimensional
many-body system with delta f unction interactions, exhibiting a BCS-BEC
crossover. It is shown that in the B CS regime the chemical potential can be
expressed solely in terms of the ground -state energy per particle. A brief
discussion is also included of the strong c oupling BEC limit.Comment: 4 pages 3 figure
Symmetry breaking and singularity structure in Bose-Einstein condensates
We determine the trajectories of vortex singularities that arise after a
single vortex is broken by a discretely symmetric impulse in the context of
Bose-Einstein condensates in a harmonic trap. The dynamics of these
singularities are analyzed to determine the form of the imprinted motion. We
find that the symmetry-breaking process introduces two effective forces: a
repulsive harmonic force that causes the daughter trajectories to be ejected
from the parent singularity, and a Magnus force that introduces a torque about
the axis of symmetry. For the analytical non-interacting case we find that the
parent singularity is reconstructed from the daughter singularities after one
period of the trapping frequency. The interactions between singularities in the
weakly interacting system do not allow the parent vortex to be reconstructed.
Analytic trajectories were compared to the actual minima of the wavefunction,
showing less 0.5% error for impulse strength of (v=0.00005). We show that these
solutions are valid within the impulse regime for various impulse strengths
using numerical integration of the Gross-Pitaevskii equation. We also show that
the actual duration of the symmetry breaking potential does not significantly
change the dynamics of the system as long as the strength is below (v=0.0005).Comment: 14 pages, 10 figure
Mutual information between geomagnetic indices and the solar wind as seen by WIND : implications for propagation time estimates
The determination of delay times of solar wind conditions at the sunward libration point to effects on Earth is investigated using mutual information. This measures the amount of information shared between two timeseries. We consider the mutual information content of solar wind observations, from WIND, and the geomagnetic indices. The success of five commonly used schemes for estimating interplanetary propagation times is examined. Propagation assuming a fixed plane normal at 45 degrees to the GSE x-axis (i.e. the Parker Spiral estimate) is found to give optimal mutual information. The mutual information depends on the point in space chosen as the target for the propagation estimate, and we find that it is maximized by choosing a point in the nightside rather than dayside magnetosphere. In addition, we employ recurrence plot analysis to visualize contributions to the mutual information, this suggests that it appears on timescales of hours rather than minutes
The Bulk RS KK-gluon at the LHC
We study the possibility of discovering and measuring the properties of the
lightest Kaluza-Klein excitation of the gluon in a Randall-Sundrum scenario
where the Standard Model matter and gauge fields propagate in the bulk. The
KK-gluon decays primarily into top quarks. We discuss how to use the final states to discover and probe the properties of the KK-gluon.
Identification of highly energetic tops is crucial for this analysis. We show
that conventional identification methods relying on well separated decay
products will not work for heavy resonances but suggest alternative methods for
top identification for energetic tops. We find, conservatively, that resonances
with masses less than 5 TeV can be discovered if the algorithm to identify high
tops can reject the QCD background by a factor of 10. We also find that
for similar or lighter masses the spin can be determined and for lighter masses
the chirality of the coupling to can be measured. Since the energetic
top pair final state is a generic signature for a large class of new physics as
the top quark presumably couples most strongly to the electroweak symmetry
breaking sector, the methods we have outlined to study the properties of the
KK-gluon should also be important in other scenarios.Comment: 21 pages, 13 figure
Statistical Description of Hydrodynamic Processes in Ionic Melts with taking into account Polarization Effects
Statistical description of hydrodynamic processes for ionic melts is proposed
with taking into account polarization effects caused by the deformation of
external ionic shells. This description is carried out by means of the Zubarev
nonequilibrium statistical operator method, appropriate for investigations of
both strong and weak nonequilibrium processes. The nonequilibrium statistical
operator and the generalized hydrodynamic equations that take into account
polarization processes are received for ionic-polarization model of ionic
molten salts when the nonequilibrium averaged values of densities of ions
number, their momentum, dipole momentum and total energy are chosen for the
reduced description parameters. A spectrum of collective excitations is
investigated within the viscoelastic approximation for ion-polarization model
of ionic melts.Comment: 24 pages, RevTex4.1-format, no figure
The Population Dynamics of Two Rodents in Two Coastal Marshes in Virginia
The communities of small mammals were evaluated for 13 months with capture-mark-recapture methods in two Spartina-Juncus marshes of the Atlantic coast in Northampton County, Virginia. Small mammals were trapped for three days each month using live traps placed on floats on two study grids. Two rodents were numerically dominant (~90% of small mammals) there: marsh rice rat, Oryzomys palustris, and meadow vole, Microtus pennsylvanicus. Monthly estimates of population density were greater for rice rats (peak: 45/ha) than for those of meadow voles (peak: 30/ha). Survival rates were generally low, especially for rice rats, indicating highly vagile populations. Both species had greatest breeding activity in spring and autumn, with lower rates in summer and winter. Sex ratios favored males in rice rats but were unity in meadow voles. Although marsh rice rats, being semi-aquatic and capable swimmers, are more highly adapted to living in flooded marsh environments, meadow voles can thrive there too
Commissioning of the LHC Current Leads
The powering of the LHC superconducting magnets relies on more than 3000 current leads transporting the current to/from the cryogenic environment and rated at currents ranging from 60 A to 13000 A. The design of these leads, about 1000 of which are based on high temperature superconducting material, was entirely done at CERN, where prototype assemblies were also assembled and tested, while the series production and testing was done in external laboratories and companies on the basis of build-to-print specifications. This report summarizes the results of the tests performed during the commissioning of the LHC machine, when the leads underwent the thermal and electrical cycles necessary for the powering of the LHC superconducting circuit
A Three Dimensional Lattice of Ion Traps
We propose an ion trap configuration such that individual traps can be
stacked together in a three dimensional simple cubic arrangement. The isolated
trap as well as the extended array of ion traps are characterized for different
locations in the lattice, illustrating the robustness of the lattice of traps
concept. Ease in the addressing of ions at each lattice site, individually or
simultaneously, makes this system naturally suitable for a number of
experiments. Application of this trap to precision spectroscopy, quantum
information processing and the study of few particle interacting system are
discussed.Comment: 4 pages, 4 Figures. Fig 1 appears as a composite of 1a, 1b, 1c and
1d. Fig 2 appears as a composite of 2a, 2b and 2
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