556 research outputs found
Mean-field dynamics of a non-Hermitian Bose-Hubbard dimer
We investigate an -particle Bose-Hubbard dimer with an additional
effective decay term in one of the sites. A mean-field approximation for this
non-Hermitian many-particle system is derived, based on a coherent state
approximation. The resulting nonlinear, non-Hermitian two-level dynamics, in
particular the fixed point structures showing characteristic modifications of
the self-trapping transition, are analyzed. The mean-field dynamics is found to
be in reasonable agreement with the full many-particle evolution.Comment: 4 pages, 3 figures, published versio
Maxwell-Chern-Simons Models: Their Symmetries, Exact Solutions and Non-relativistic Limits
Two Maxwell-Chern-Simons (MCS) models in the (1 + 3)-dimensional space-space are discussed and families of their exact solutions are found. In contrast to the Carroll-Field-Jackiw (CFE) model [2] these systems are relativistically invariant and include the CFJ model as a particular sector.Using the InNonNu-Wigner contraction a Galilei-invariant non-relativistic limit of the systems is found, which makes possible to find a Galilean formulation of the CFJ model
Symmetries and solutions of field equations of axion electrodynamics
The group classification of models of axion electrodynamics with arbitrary
self interaction of axionic field is carried out. It is shown that extensions
of the basic Poincar\'e invariance of these models appear only for constant and
exponential interactions. The related conservation laws are discussed. Using
the In\"on\"u-Wigner contraction the non-relativistic limit of equations of
axion electrodynamics is found. An extended class of exact solutions for the
electromagnetic and axion fields is obtained. Among them there are solutions
including up to six arbitrary functions. In particular, solutions which
describe propagation with velocities faster than the velocity of light are
found. These solutions are smooth and bounded functions which correspond to
positive definite and bounded energy density.Comment: New section 6 ia added where the superluminal propagation velocities
are discusse
Galilei invariant theories. I. Constructions of indecomposable finite-dimensional representations of the homogeneous Galilei group: directly and via contractions
All indecomposable finite-dimensional representations of the homogeneous
Galilei group which when restricted to the rotation subgroup are decomposed to
spin 0, 1/2 and 1 representations are constructed and classified. These
representations are also obtained via contractions of the corresponding
representations of the Lorentz group. Finally the obtained representations are
used to derive a general Pauli anomalous interaction term and Darwin and
spin-orbit couplings of a Galilean particle interacting with an external
electric field.Comment: 23 pages, 2 table
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