8,854 research outputs found
Interactive solution-adaptive grid generation procedure
TURBO-AD is an interactive solution adaptive grid generation program under development. The program combines an interactive algebraic grid generation technique and a solution adaptive grid generation technique into a single interactive package. The control point form uses a sparse collection of control points to algebraically generate a field grid. This technique provides local grid control capability and is well suited to interactive work due to its speed and efficiency. A mapping from the physical domain to a parametric domain was used to improve difficulties encountered near outwardly concave boundaries in the control point technique. Therefore, all grid modifications are performed on the unit square in the parametric domain, and the new adapted grid is then mapped back to the physical domain. The grid adaption is achieved by adapting the control points to a numerical solution in the parametric domain using control sources obtained from the flow properties. Then a new modified grid is generated from the adapted control net. This process is efficient because the number of control points is much less than the number of grid points and the generation of the grid is an efficient algebraic process. TURBO-AD provides the user with both local and global controls
Two Circular-Rotational Eigenmodes in Vortex Gyrotropic Motions in Soft Magnetic Nanodots
We found, by micromagnetic numerical and analytical calculations, that the
clockwise (CW) and counterclockwise (CCW) circular-rotational motions of a
magnetic vortex core in a soft magnetic circular nanodot are the elementary
eigenmodes existing in the gyrotropic motion with respect to the corresponding
CW and CCW circular-rotational-field eigenbasis. Any steady-state vortex
gyrotropic motions driven by a linearly polarized oscillating in-plane magnetic
field in the linear regime can be perfectly understood according to the
superposition of the two circular eigenmodes, which show asymmetric resonance
characteristics reflecting the vortex polarization. The relative magnitudes in
the amplitude and phase between the CCW and CW eigenmodes determine the
elongation and orientation of the orbital trajectories of the vortex core
motions, respectively, which trajectories vary with the polarization and
chirality of the given vortex as well as the field frequency across the
resonance frequency.Comment: 30 pages, 7 figure
Signatures for doubly-charged Higgsinos at colliders
Several supersymmetric models with extended gauge structures predict light
doubly-charged Higgsinos. Their distinctive signature at the large hadron
collider is highlighted by studying their production and decay characteristics.Comment: 3 pages, 4 figures, Latex. Submitted for SUSY 2008 proceeding
Zero Temperature Chiral Phase Transition in (2+1)-Dimensional QED with a Chern-Simons Term
We investigate the zero temperature chiral phase transition in
(2+1)-dimensional QED in the presence of a Chern-Simons term, changing the
number of fermion flavors. In the symmetric phase, there are no light degrees
of freedom even at the critical point. Unlike the case without a Chern-Simons
term, the phase transition is first-order.Comment: 7 pages, RevTeX, no figure
Precise Complexity of the Core in Dichotomous and Additive Hedonic Games
Hedonic games provide a general model of coalition formation, in which a set
of agents is partitioned into coalitions, with each agent having preferences
over which other players are in her coalition. We prove that with additively
separable preferences, it is -complete to decide whether a core- or
strict-core-stable partition exists, extending a result of Woeginger (2013).
Our result holds even if valuations are symmetric and non-zero only for a
constant number of other agents. We also establish -completeness of
deciding non-emptiness of the strict core for hedonic games with dichotomous
preferences. Such results establish that the core is much less tractable than
solution concepts such as individual stability.Comment: ADT-2017, 15 pages in LNCS styl
Controlling the topological sector of magnetic solitons in exfoliated CrNbS crystals
We investigate manifestations of topological order in monoaxial helimagnet
CrNbS by performing transport measurements on ultra-thin crystals.
Upon sweeping the magnetic field perpendicularly to the helical axis, crystals
thicker than one helix pitch (48 nm) but much thinner than the magnetic domain
size (1 m) are found to exhibit sharp and hysteretic resistance
jumps. We show that these phenomena originate from transitions between
topological sectors with different number of magnetic solitons. This is
confirmed by measurements on crystals thinner than 48 nm --in which the
topological sector cannot change-- that do not exhibit any jump or hysteresis.
Our results show the ability to deterministically control the topological
sector of finite-size CrNbS and to detect inter-sector transitions
by transport measurements.Comment: 7 pages, 8 figure
Quantum Number Density Asymmetries Within QCD Jets Correlated With Lambda Polarization
The observation of jets in a variety of hard-scattering processes has allowed
the quantitative study of perturbative quantum chromodynamics (PQCD) by
comparing detailed theoretical predictions with a wide range of experimental
data. This paper examines how some important, nonperturbative, facets of QCD
involving the internal dynamical structure of jets can be studied by measuring
the spin orientation of Lambda particles produced in these jets. The
measurement of the transverse polarization for an individual Lambda within a
QCD jet permits the definition of spin-directed asymmetries in local quantum
number densities in rapidity space (such as charge, strangeness and baryon
number densities) involving neighboring hadrons in the jet. These asymmetries
can only be generated by soft, nonperturbative dynamical mechanisms and such
measurements can provide insight not otherwise accessible into the color
rearrangement that occurs during the hadronization stage of the fragmentation
process.Comment: The replacement manuscript contains a new abstract, five pages of
additional material and a revised version of Fig.
Neutrino Emission from Magnetized Proto-Neutron Stars in Relativistic Mean Field Theory
We make a perturbative calculation of neutrino scattering and absorption in
hot and dense hyperonic neutron-star matter in the presence of a strong
magnetic field. We find that the absorption cross-sections show a remarkable
angular dependence in that the neutrino absorption strength is reduced in a
direction parallel to the magnetic field and enhanced in the opposite
direction. This asymmetry in the neutrino absorbtion can be as much as 2.2 % of
the entire neutrino momentum for an interior magnetic field of \sim 2 x 10^{17}
G. We estimate the pulsar kick velocities associated with this asymmetry in a
fully relativistic mean-field theory formulation. We show that the kick
velocities calculated here are comparable to observed pulsar velocities.Comment: arXiv admin note: substantial text overlap with arXiv:1009.097
Neutrino reactions via neutral and charged current by Quasi-particle Random Phase Approximation(QRPA)
We developed the quasi-particle random phase approximation (QRPA) for the
neutrino scattering off even-even nuclei via neutral current (NC) and charged
cur- rent (CC). The QRPA has been successfully applied for the \beta and
\beta\beta decay of relevant nuclei. To describe neutrino scattering, general
multipole transitions by weak interactions with a finite momentum transfer are
calculated for NC and CC reaction with detailed formalism. Since we consider
neutron-proton (np) pairing as well as neutron-neutron (nn) and proton-proton
(pp) pairing correlations, the nn + pp QRPA and np QRPA are combined in a
framework, which enables to describe both NC and CC reactions in a consistent
way. Numerical results for \nu-^{12}C, -^{56}Fe and -^{56}Ni reactions are
shown to comply with other theoretical calculations and reproduce well
available experimental data
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