1,476 research outputs found
The Dirac particle on central backgrounds and the anti-de Sitter oscillator
It is shown that, for spherically symmetric static backgrounds, a simple
reduced Dirac equation can be obtained by using the Cartesian tetrad gauge in
Cartesian holonomic coordinates. This equation is manifestly covariant under
rotations so that the spherical coordinates can be separated in terms of
angular spinors like in special relativity, obtaining a pair of radial
equations and a specific form of the radial scalar product. As an example, we
analytically solve the anti-de Sitter oscillator giving the formula of the
energy levels and the form of the corresponding eigenspinors.Comment: 16 pages, Late
On the computation of the term of the series defining the center manifold for a scalar delay differential equation
In computing the third order terms of the series of powers of the center
manifold at an equilibrium point of a scalar delay differential equation, with
a single constant delay some problems occur at the term
More precisely, in order to determine the values at 0,
respectively of the function an algebraic system of
equations must be solved. We show that the two equations are dependent, hence
the system has an infinity of solutions. Then we show how we can overcome this
lack of uniqueness and provide a formula for Comment: Presented at the Conference on Applied and Industrial Mathematics-
CAIM 2011, Iasi, Romania, 22-25 September, 2011. Preprin
Geometric models of (d+1)-dimensional relativistic rotating oscillators
Geometric models of quantum relativistic rotating oscillators in arbitrary
dimensions are defined on backgrounds with deformed anti-de Sitter metrics. It
is shown that these models are analytically solvable, deriving the formulas of
the energy levels and corresponding normalized energy eigenfunctions. An
important property is that all these models have the same nonrelativistic
limit, namely the usual harmonic oscillator.Comment: 7 pages, Late
Kondo Temperature in Multilevel Quantum Dots
We develop a general method to evaluate the Kondo temperature in a multilevel
quantum dot that is weakly coupled to conducting leads. Our theory reveals that
the Kondo temperature is strongly enhanced when the intradot energy-level
spacing is comparable to or smaller than the charging energy. We propose an
experiment to test our result, which consists of measuring the size-dependence
of the Kondo temperature.Comment: 4 pages, 1 figure and supplementary material. Revised and improved
version, to appear in Phys. Rev. Let
Approximative analytical solutions of the Dirac equation in Schwarzschild spacetime
Approximative analytic solutions of the Dirac equation in the geometry of
Schwarzschild black holes are derived obtaining information about the discrete
energy levels and the asymptotic behavior of the energy eigenspinors.Comment: 8 page
Gilbert Damping in Conducting Ferromagnets II: Model Tests of the Torque-Correlation Formula
We report on a study of Gilbert damping due to particle-hole pair excitations
in conducting ferromagnets. We focus on a toy two-band model and on a four-band
spherical model which provides an approximate description of ferromagnetic
(Ga,Mn)As. These models are sufficiently simple that disorder-ladder-sum vertex
corrections to the long-wavelength spin-spin response function can be summed to
all orders. An important objective of this study is to assess the reliability
of practical approximate expressions which can be combined with electronic
structure calculations to estimate Gilbert damping in more complex systems.Comment: 10 pages, 10 figures. Submitted to Phys. Rev.
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