6,199 research outputs found
Impurity in the Tomonaga-Luttinger model: a Functional Integral Approach
In this tutorial notes we review a functional bosonization approach in the
Keldysh technique to one-dimensional Luttinger liquid in the presence of an
impurity.Comment: 15 pages, 1 figure, Proceedings of LXXXI Les Houches School on
"Nanoscopic quantum transport", Les Houches, France, June 28-July 30, 200
Many-body effects in Landau levels: Non-commutative geometry and squeezed correlated states
We discuss symmetry-driven squeezing and coherent states of few-particle
systems in magnetic fields. An operator approach using canonical
transformations and the SU(1,1) algebras is developed for considering Coulomb
correlations in the lowest Landau levels.Comment: 3 pages, 2 figures; to be reported at 17th Int. Conf. on High
Magnetic Fields in Semiconductor Physics, Wuerzburg, Germany, July 30 - Aug
4, 200
Superfluidity of "dirty" indirect excitons and magnetoexcitons in two-dimensional trap
The superfluid phase transition of bosons in a two-dimensional (2D) system
with disorder and an external parabolic potential is studied. The theory is
applied to experiments on indirect excitons in coupled quantum wells. The
random field is allowed to be large compared to the dipole-dipole repulsion
between excitons. The slope of the external parabolic trap is assumed to change
slowly enough to apply the local density approximation (LDA) for the superfluid
density, which allows us to calculate the Kosterlitz-Thouless temperature
at each local point of the trap. The superfluid phase occurs
around the center of the trap () with the normal phase outside
this area. As temperature increases, the superfluid area shrinks and disappears
at temperature . Disorder acts to deplete the condensate; the
minimal total number of excitons for which superfluidity exists increases with
disorder at fixed temperature. If the disorder is large enough, it can destroy
the superfluid entirely. The effect of magnetic field is also calculated for
the case of indirect excitons. In a strong magnetic field , the superfluid
component decreases, primarily due to the change of the exciton effective mass.Comment: 13 pages, 3 figure
Pseudo diamagnetism of four component exciton condensates
We analyze the spin structure of the ground state of four-component exciton
condensates in coupled quantum wells as a function of spin-dependent
interactions and applied magnetic field. The four components correspond to the
degenerate exciton states characterized by and spin projections
to the axis of the structure. We show that in a wide range of parameters, the
chemical potential of the system increases as a function of magnetic field,
which manifests a pseudo-diamagnetism of the system. The transitions to
polarized two- and one-component condensates can be of the first-order in this
case. The predicted effects are caused by energy conserving mixing of
and excitons.Comment: 4 pages, 2 figure
The Level Spacing Distribution Near the Anderson Transition
For a disordered system near the Anderson transition we show that the
nearest-level-spacing distribution has the asymptotics for s\gg \av{s}\equiv 1 which is universal and intermediate
between the Gaussian asymptotics in a metal and the Poisson in an insulator.
(Here the critical exponent and the numerical coefficient
depend only on the dimensionality ). It is obtained by mapping the energy
level distribution to the Gibbs distribution for a classical one-dimensional
gas with a pairwise interaction. The interaction, consistent with the universal
asymptotics of the two-level correlation function found previously, is proved
to be the power-law repulsion with the exponent .Comment: REVTeX, 8 pages, no figure
Impurity Scattering in Luttinger Liquid with Electron-Phonon Coupling
We study the influence of electron-phonon coupling on electron transport
through a Luttinger liquid with an embedded weak scatterer or weak link. We
derive the renormalization group (RG) equations which indicate that the
directions of RG flows can change upon varying either the relative strength of
the electron-electron and electron-phonon coupling or the ratio of Fermi to
sound velocities. This results in the rich phase diagram with up to three fixed
points: an unstable one with a finite value of conductance and two stable ones,
corresponding to an ideal metal or insulator.Comment: 4 pages, 2 figure
Theoretical considerations of some nonlinear aspects of hypersonic panel flutter Annual report, 1 Sep. 1967 - 31 Aug. 1968
Stability and postcritical response of infinite width panels on hinged supports due to aerodynamic loads at hypersonic spee
Невизначеність, ризики, прибуток
The principles of accounting and estimations of probabilistic character of productive activity of enterprises, accepted in the methodology of accounting of uncertainty and risks, worked out by the author of this researches , are stated. The methodology is based on the fundamental postulates of probability theory, the theories of functions linearization and on the qualitative and quantitative technico-economical analysis in decision making are discussed. An example of the using this methodology with the solutions optimization is given. This methodology was adapted by the author over the past 10-15 years.В статье приведены основные принципы учета и оценки вероятностного характера производственной деятельности предприятий, принятые в методологии учета неопределенности и рисков, разработанной автором этого исследования. Указанная методология базируется на основных постулатах теории вероятностей, теории линеаризации функций и на качественном и количественном технико-экономическом анализе при принятии решений. Дан пример использования указанной методологии при оптимизации этих решений. Указанная методология адаптирована автором на протяжении последних 10-15 лет.У статті наведені основні принципи обліку та оцінки імовірнісного характеру виробничої діяльності підприємств, прийняті в методології обліку невизначеності і ризиків, розробленій автором цього дослідження. Вказана методологія базується на основних постулатах теорії вірогідності, теорії лінеаризації функцій і на якісному і кількісному техніко-економічному аналізі при ухваленні рішень. Наданий приклад використання вказаної методології при оптимізації цих рішень. Вказана методологія адаптована автором упродовж останніх 10-15 років
Gauge singlet scalar as inflaton and thermal relic dark matter
We show that, by adding a gauge singlet scalar S to the standard model which
is nonminimally coupled to gravity, S can act both as the inflaton and as
thermal relic dark matter. We obtain the allowed region of the (m_s, m_h)
parameter space which gives a spectral index in agreement with observational
bounds and also produces the observed dark matter density while not violating
vacuum stability or nonperturbativity constraints. We show that, in contrast to
the case of Higgs inflation, once quantum corrections are included the spectral
index is significantly larger than the classical value (n = 0.966 for N = 60)
for all allowed values of the Higgs mass m_h. The range of Higgs mass
compatible with the constraints is 145 GeV < m_h < 170 GeV. The S mass lies in
the range 45 GeV < ms < 1 TeV for the case of a real S scalar with large
quartic self-coupling lambdas, with a smaller upper bound for smaller lambdas.
A region of the parameter space is accessible to direct searches at the LHC via
h-->SS, while future direct dark matter searches should be able to
significantly constrain the model.Comment: 13 pages, 7 figures. Published versio
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