5,529 research outputs found
Theory of transient spectroscopy of multiple quantum well structures
A theory of the transient spectroscopy of quantum well (QW) structures under
a large applied bias is presented. An analytical model of the initial part of
the transient current is proposed. The time constant of the transient current
depends not only on the emission rate from the QWs, as is usually assumed, but
also on the subsequent carrier transport across QWs. Numerical simulation was
used to confirm the validity of the proposed model, and to study the transient
current on a larger time scale. It is shown that the transient current is
influenced by the nonuniform distribution of the electric field and related
effects, which results in a step-like behavior of the current. A procedure of
extraction of the QW emission time from the transient spectroscopy experiments
is suggested.Comment: 5 pages, 4 figures, to be published in J. Appl. Phy
On the susceptibility function of piecewise expanding interval maps
We study the susceptibility function Psi(z) associated to the perturbation
f_t=f+tX of a piecewise expanding interval map f. The analysis is based on a
spectral description of transfer operators. It gives in particular sufficient
conditions which guarantee that Psi(z) is holomorphic in a disc of larger than
one. Although Psi(1) is the formal derivative of the SRB measure of f_t with
respect to t, we present examples satisfying our conditions so that the SRB
measure is not Lipschitz.*We propose a new version of Ruelle's conjectures.* In
v2, we corrected a few minor mistakes and added Conjectures A-B and Remark 4.5.
In v3, we corrected the perturbation (X(f(x)) instead of X(x)), in particular
in the examples from Section 6. As a consequence, Psi(z) has a pole at z=1 for
these examples.Comment: To appear Comm. Math. Phy
Collective motions in globally coupled tent maps with stochastic updating
We study a generalization of globally coupled maps, where the elements are
updated with probability . When is below a threshold , the
collective motion vanishes and the system is the stationary state in the large
size limit. We present the linear stability analysis.Comment: 6 pages including 5 figure
Noiseless Collective Motion out of Noisy Chaos
We consider the effect of microscopic external noise on the collective motion
of a globally coupled map in fully desynchronized states. Without the external
noise a macroscopic variable shows high-dimensional chaos distinguishable from
random motion. With the increase of external noise intensity, the collective
motion is successively simplified. The number of effective degrees of freedom
in the collective motion is found to decrease as with the
external noise variance . It is shown how the microscopic noise can
suppress the number of degrees of freedom at a macroscopic level.Comment: 9 pages RevTex file and 4 postscript figure
Perturbation theory for self-gravitating gauge fields I: The odd-parity sector
A gauge and coordinate invariant perturbation theory for self-gravitating
non-Abelian gauge fields is developed and used to analyze local uniqueness and
linear stability properties of non-Abelian equilibrium configurations. It is
shown that all admissible stationary odd-parity excitations of the static and
spherically symmetric Einstein-Yang-Mills soliton and black hole solutions have
total angular momentum number , and are characterized by
non-vanishing asymptotic flux integrals. Local uniqueness results with respect
to non-Abelian perturbations are also established for the Schwarzschild and the
Reissner-Nordstr\"om solutions, which, in addition, are shown to be linearly
stable under dynamical Einstein-Yang-Mills perturbations. Finally, unstable
modes with are also excluded for the static and spherically
symmetric non-Abelian solitons and black holes.Comment: 23 pages, revtex, no figure
Monopoles, Dyons and Black Holes in the Four-Dimensional Einstein-Yang-Mills Theory
A continuum of monopole, dyon and black hole solutions exist in the
Einstein-Yang-Mills theory in asymptotically anti-de Sitter space. Their
structure is studied in detail. The solutions are classified by non-Abelian
electric and magnetic charges and the ADM mass. The stability of the solutions
which have no node in non-Abelian magnetic fields is established. There exist
critical spacetime solutions which terminate at a finite radius, and have
universal behavior. The moduli space of the solutions exhibits a fractal
structure as the cosmological constant approaches zero.Comment: 36 Pages, 16 Figures. Minor typos corrected and one figure modifie
Scattering into Cones and Flux across Surfaces in Quantum Mechanics: a Pathwise Probabilistic Approach
We show how the scattering-into-cones and flux-across-surfaces theorems in
Quantum Mechanics have very intuitive pathwise probabilistic versions based on
some results by Carlen about large time behaviour of paths of Nelson
diffusions. The quantum mechanical results can be then recovered by taking
expectations in our pathwise statements.Comment: To appear in Journal of Mathematical Physic
Three-body correlations in direct reactions: Example of Be populated in reaction
The Be continuum states were populated in the charge-exchange reaction
H(Li,Be) collecting very high statistics data ( events) on the three-body ++ correlations. The
Be excitation energy region below MeV is considered, where the
data are dominated by contributions from the and states. It is
demonstrated how the high-statistics few-body correlation data can be used to
extract detailed information on the reaction mechanism. Such a derivation is
based on the fact that highly spin-aligned states are typically populated in
the direct reactions.Comment: submitted to Physical Review
Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction
A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and
width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state
is consistent with a number of broad resonances predicted by recent cluster
model calculations. The well-established reaction mechanism, combined with a
simple and transparent analysis procedure confers considerable validity to this
observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication
in Phys. Rev. C, August, 200
ДОСЛІДЖЕННЯ ВПЛИВУ ХАОТИЧНОГО СТРУМУ ЕЛЕКТРОНІВ НА ПАРАМЕТРИ ЕЛЕКТРИЧНОГО ПОЛЯ У ПРИАНОДНІЙ ЗОНІ РОЗРЯДУ
The influence of the ratio of the discharge density and chaotic electronic currents on the potential drop in the diffusion zone near the anode was considered. The analysis of the influence of forced convection on the conditions of existence of a stable diffuse discharge on the anode surface was performedРассмотрено влияние соотношения плотности разрядного и хаотического электронных токов на падение потенциала в диффузионной зоне прианодной области. Выполнен анализ влияния вынужденной конвекции на условия существования устойчивого диффузного разряда на поверхности анода.Розглянуто вплив співвідношення густини розрядного та хаотичного електронних струмів на падіння потенціалу у дифузійній зоні прианодної області. Виконано аналіз впливу вимушеної конвекції на умови існування стійкого дифузного розряду на поверхні анода
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