146 research outputs found
Bose-representation for a strongly coupled nonequilibrim fermionic superfluid in a time-dependent trap
Using the functional integral formulation of a nonequilibrium quantum
many-body theory we develop a regular description of a Fermi system with a
strong attractive interaction in the presence of an external time-dependent
potential. In the strong coupling limit this fermionic system is equivalent to
a noequilibrium dilute Bose gas of diatomic molecules. We also consider a
nonequilibrim strongly coupled Bardeen-Cooper-Schrieffer (BCS) theory and show
that it reduces to the full nonlinear time-dependent Gross-Pitaevski (GP)
equation, which determines an evolution of the condensate wave function.Comment: RevTeX 4, 6 pages, 2 eps figure
Symmetric space sigma-model dynamics: Current formalism
After explicitly constructing the symmetric space sigma model lagrangian in
terms of the coset scalars of the solvable Lie algebra gauge in the current
formalism we derive the field equations of the theory.Comment: 10 page
Field-asymmetric transverse magnetoresistance in a nonmagnetic quantum-size structure
A new phenomenon is observed experimentally in a heavily doped asymmetric
quantum-size structure in a magnetic field parallel to the quantum-well layers
- a transverse magnetoresistance which is asymmetric in the field (there can
even be a change in sign) and is observed in the case that the structure has a
built-in lateral electric field. A model of the effect is proposed. The
observed asymmetry of the magnetoresistance is attributed to an additional
current contribution that arises under nonequilibrium conditions and that is
linear in the gradient of the electrochemical potential and proportional to the
parameter characterizing the asymmetry of the spectrum with respect to the
quasimomentum.Comment: 10 pages, 5 figures. For correspondence, mail to
[email protected]
On the Symmetric Space Sigma-Model Kinematics
The solvable Lie algebra parametrization of the symmetric spaces is
discussed. Based on the solvable Lie algebra gauge two equivalent formulations
of the symmetric space sigma model are studied. Their correspondence is
established by inspecting the normalization conditions and deriving the field
transformation laws.Comment: 17 page
On the Cartan Model of the Canonical Vector Bundles over Grassmannians
We give a representation of canonical vector bundles over Grassmannian
manifolds as non-compact affine symmetric spaces as well as their Cartan model
in the group of the Euclidean motions.Comment: 6 page
Contractions of Low-Dimensional Lie Algebras
Theoretical background of continuous contractions of finite-dimensional Lie
algebras is rigorously formulated and developed. In particular, known necessary
criteria of contractions are collected and new criteria are proposed. A number
of requisite invariant and semi-invariant quantities are calculated for wide
classes of Lie algebras including all low-dimensional Lie algebras.
An algorithm that allows one to handle one-parametric contractions is
presented and applied to low-dimensional Lie algebras. As a result, all
one-parametric continuous contractions for the both complex and real Lie
algebras of dimensions not greater than four are constructed with intensive
usage of necessary criteria of contractions and with studying correspondence
between real and complex cases.
Levels and co-levels of low-dimensional Lie algebras are discussed in detail.
Properties of multi-parametric and repeated contractions are also investigated.Comment: 47 pages, 4 figures, revised versio
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