3,212 research outputs found
How to relate the oscillator and Coulomb systems on spheres and pseudospheres?
We show that the oscillators on a sphere and pseudosphere are related, by the
so-called Bohlin transformation, with the Coulomb systems on the pseudosphere:
the even states of an oscillator yields the conventional Coulomb system on
pseudosphere, while the odd states yield the Coulomb system on pseudosphere in
the presence of magnetic flux tube generating half spin. In the higher
dimensions the oscillator and Coulomb(-like) systems are connected in the
similar way. In particular, applying the Kustaanheimo-Stiefel transformation to
the oscillators on sphere and pseudosphere, we obtained the preudospherical
generalization of MIC-Kepler problem describing three-dimensional charge-dyon
system.Comment: 12 pages, Based on talk given at XXIII Colloquium on Group
Theoretical Methods in Physics (July 31-August 5, 2000, Dubna
A Generalization of the Kepler Problem
We construct and analyze a generalization of the Kepler problem. These
generalized Kepler problems are parameterized by a triple
where the dimension is an integer, the curvature is a real
number, the magnetic charge is a half integer if is odd and is 0 or
1/2 if is even. The key to construct these generalized Kepler problems is
the observation that the Young powers of the fundamental spinors on a punctured
space with cylindrical metric are the right analogues of the Dirac monopoles.Comment: The final version. To appear in J. Yadernaya fizik
Effects of high-field electrical stress on the conduction properties of ultra-thin La2O3 films
Electron transport in high-field stressed metal-insulator-silicon devices with ultrathin (<5nm) lanthanum oxide layers is investigated. We show that the leakage current flowing through the structure prior to degradation is direct and Fowler-Nordheimtunneling conduction, while that after stress exhibits diode-like behavior with series and parallel resistances. In this latter case, a closed-form expression for the current-voltage characteristic, based on the Lambert W function, is presented. Current evolution from one regime to the other during constant voltage stress takes place by means of discrete current steps of nearly identical magnitude, which would be indicative of the occurrence of multiple dielectric breakdowns across the insulating layer
Generalized Taub-NUT metrics and Killing-Yano tensors
A necessary condition that a St\"ackel-Killing tensor of valence 2 be the
contracted product of a Killing-Yano tensor of valence 2 with itself is
re-derived for a Riemannian manifold. This condition is applied to the
generalized Euclidean Taub-NUT metrics which admit a Kepler type symmetry. It
is shown that in general the St\"ackel-Killing tensors involved in the
Runge-Lenz vector cannot be expressed as a product of Killing-Yano tensors. The
only exception is the original Taub-NUT metric.Comment: 14 pages, LaTeX. Final version to appear in J.Phys.A:Math.Ge
muCool: A novel low-energy muon beam for future precision experiments
Experiments with muons () and muonium atoms () offer
several promising possibilities for testing fundamental symmetries. Examples of
such experiments include search for muon electric dipole moment, measurement of
muon and experiments with muonium from laser spectroscopy to gravity
experiments. These experiments require high quality muon beams with small
transverse size and high intensity at low energy.
At the Paul Scherrer Institute, Switzerland, we are developing a novel device
that reduces the phase space of a standard beam by a factor of
with efficiency. The phase space compression is achieved by
stopping a standard beam in a cryogenic helium gas. The stopped
are manipulated into a small spot with complex electric and magnetic
fields in combination with gas density gradients. From here, the muons are
extracted into the vacuum and into a field-free region. Various aspects of this
compression scheme have been demonstrated. In this article the current status
will be reported.Comment: 8 pages, 5 figures, TCP 2018 conference proceeding
On two superintegrable nonlinear oscillators in N dimensions
We consider the classical superintegrable Hamiltonian system given by
, where U
is known to be the "intrinsic" oscillator potential on the Darboux spaces of
nonconstant curvature determined by the kinetic energy term T and parametrized
by {\lambda}. We show that H is Stackel equivalent to the free Euclidean
motion, a fact that directly provides a curved Fradkin tensor of constants of
motion for H. Furthermore, we analyze in terms of {\lambda} the three different
underlying manifolds whose geodesic motion is provided by T. As a consequence,
we find that H comprises three different nonlinear physical models that, by
constructing their radial effective potentials, are shown to be two different
nonlinear oscillators and an infinite barrier potential. The quantization of
these two oscillators and its connection with spherical confinement models is
briefly discussed.Comment: 11 pages; based on the contribution to the Manolo Gadella Fest-60
years-in-pucelandia, "Recent advances in time-asymmetric quantum mechanics,
quantization and related topics" hold in Valladolid (Spain), 14-16th july
201
Photoinduced metallic properties of one-dimensional strongly correlated electron systems
We study photoinduced optical responses of one-dimensional strongly
correlated electron systems. The optical conductivity spectra are calculated
for the ground state and a photoexcited state in the one-dimensional Hubbard
model at half filling by using the exact diagonalization method. It is found
that, in the Mott insulator phase, the photoexcited state has large spectral
weights including the Drude weight below the optical gap. As a consequence, the
spectral weight above the optical gap is largely reduced. These results imply
that a metallic state is induced by photoexcitation. Comparison between the
photoexcited and hole-doped states shows that the photoexcitation is similar to
chemical doping.Comment: 4 pages, 4 figures, submitted to J. Phys. Soc. Jp
Effect of temperature on the cavitation erosion of cast iron
Vibratory cavitation erosion tests of gray cast iron, together with tests of tool steel and 316 stainless steel for comparison, were performed at various water temperatures and horn amplitudes under a suppression pressure of 1 bar. The erosion processes for cast iron under the highest temperatures used (200 and 230 [deg]F, i.e. 93 and 110 [deg]C) are similar to those at room temperature. For each of the materials tested, the maximum weight loss rate increases, shows a peak and then decreases with increasing temperature. However, the maximum damage temperature for cast iron decreases with amplitude, i.e. 200, 170 and 160 [deg]F (93, 77 and 71 [deg]C) for double-horn amplitudes of 1.0 x 10-3, 1.38 x 10-3 and 1.78 x 10-3 in (25.4, 35.1 and 45.2 [mu]m). The peak for tool steel and 316 stainless steel occurs at 160 [deg]F (71 [deg]C) regardless of amplitude. Liquid temperature effects for cast iron erosion were explained by considering the interrelation between corrosive action and mechanical action due to cavitation bubble collapse.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25276/1/0000719.pd
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