313 research outputs found
Anomalous magneto-oscillations and spin precession
A semiclassical analysis based on concepts developed in quantum chaos reveals
that anomalous magneto-oscillations in quasi two-dimensional systems with
spin-orbit interaction reflect the non-adiabatic spin precession of a classical
spin vector along the cyclotron orbits.Comment: 4 pages, 2 figure
High energy limits of Laplace-type and Dirac-type eigenfunctions and frame flows
We relate high-energy limits of Laplace-type and Dirac-type operators to
frame flows on the corresponding manifolds, and show that the ergodicity of
frame flows implies quantum ergodicity in an appropriate sense for those
operators. Observables for the corresponding quantum systems are matrix-valued
pseudodifferential operators and therefore the system remains non-commutative
in the high-energy limit. We discuss to what extent the space of stationary
high-energy states behaves classically.Comment: 26 pages, latex2
Figurations of Time in Asia
The experience and the ensuing structuring of time
forms a constitutive part of human cultures. There are
many ways of coming to terms with time, calendars
and historiographies being its most common cultural
representations. The contributions to this volume deal
with lesser known figurations that result directly from
the various perceptions about time and phenomena
related to time. Diachronous investigations in various
parts of Asia (predominantly South Asia) reveal a
broad spectrum of such visual and literary figurative
manifestations.
While Hinduism recognizes a divine personification
of time and allocates the ominous factor time in an
ontological proximity to death, other cultures of Asia
have developed their own specific concepts and strategies.
This collection of essays combines perspectives
of various disciplines on figurations in which time
congeals, as it were. These figurations result from local
time regimes, and beyond demonstrating their diversity
of forms this volume offers coordinates for a comparison
of cultures.
The topics include chronograms as well as early Buddhist
topoi of the vastness of time, the Indian Jaina representation
of both temporality and non-temporality and
the teachings of a Mediaeval Zen master hinting at the
more stationary aspects of time
Weyl-Underhill-Emmrich quantization and the Stratonovich-Weyl quantizer
Weyl-Underhill-Emmrich (WUE) quantization and its generalization are
considered. It is shown that an axiomatic definition of the Stratonovich-Weyl
(SW) quantizer leads to severe difficulties. Quantization on the cylinder
within the WUE formalism is discussed.Comment: 15+1 pages, no figure
Gauge Orbit Types for Theories with Classical Compact Gauge Group
We determine the orbit types of the action of the group of local gauge
transformations on the space of connections in a principal bundle with
structure group O(n), SO(n) or over a closed, simply connected manifold
of dimension 4. Complemented with earlier results on U(n) and SU(n) this
completes the classification of the orbit types for all classical compact gauge
groups over such space-time manifolds. On the way we derive the classification
of principal bundles with structure group SO(n) over these manifolds and the
Howe subgroups of SO(n).Comment: 57 page
Stratification of the orbit space in gauge theories. The role of nongeneric strata
Gauge theory is a theory with constraints and, for that reason, the space of
physical states is not a manifold but a stratified space (orbifold) with
singularities. The classification of strata for smooth (and generalized)
connections is reviewed as well as the formulation of the physical space as the
zero set of a momentum map. Several important features of nongeneric strata are
discussed and new results are presented suggesting an important role for these
strata as concentrators of the measure in ground state functionals and as a
source of multiple structures in low-lying excitations.Comment: 22 pages Latex, 1 figur
Moyal star product approach to the Bohr-Sommerfeld approximation
The Bohr-Sommerfeld approximation to the eigenvalues of a one-dimensional
quantum Hamiltonian is derived through order (i.e., including the
first correction term beyond the usual result) by means of the Moyal star
product. The Hamiltonian need only have a Weyl transform (or symbol) that is a
power series in , starting with , with a generic fixed point in
phase space. The Hamiltonian is not restricted to the kinetic-plus-potential
form. The method involves transforming the Hamiltonian to a normal form, in
which it becomes a function of the harmonic oscillator Hamiltonian.
Diagrammatic and other techniques with potential applications to other normal
form problems are presented for manipulating higher order terms in the Moyal
series.Comment: 27 pages, no figure
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