15,339 research outputs found
Correspondence in Quasiperiodic and Chaotic Maps: Quantization via the von Neumann Equation
A generalized approach to the quantization of a large class of maps on a
torus, i.e. quantization via the von Neumann Equation, is described and a
number of issues related to the quantization of model systems are discussed.
The approach yields well behaved mixed quantum states for tori for which the
corresponding Schrodinger equation has no solutions, as well as an extended
spectrum for tori where the Schrodinger equation can be solved.
Quantum-classical correspondence is demonstrated for the class of mappings
considered, with the Wigner-Weyl density going to the correct
classical limit. An application to the cat map yields, in a direct manner,
nonchaotic quantum dynamics, plus the exact chaotic classical propagator in the
correspondence limit.Comment: 36 pages, RevTex preprint forma
Exponential Divergence and Long Time Relaxation in Chaotic Quantum Dynamics
Phase space representations of the dynamics of the quantal and classical cat
map are used to explore quantum--classical correspondence in a K-system: as
, the classical chaotic behavior is shown to emerge smoothly and
exactly. The quantum dynamics near the classical limit displays both
exponential separation of adjacent distributions and long time relaxation, two
characteristic features of classical chaotic motion.Comment: 10 pages, ReVTeX, to appear in Phys. Rev. Lett. 13 figures NOT
included. Available either as LARGE (uuencoded gzipped) postscript files or
hard-copies from [email protected]
On Spin-driven inflation from fields in General Relativity and COBE data
Obukhov spin-driven inflation in General Relativity is extended to include
inflaton fields.A de Sitter phase solution is obtained and new slow-rolling
conditions for the spin potential are obtained.The spin potential reduces to
Obukhov result at the present epoch of the Universe where the spin density is
low with comparison to the Early Universe spin densities.A relation betwenn the
spin density energy and the temperature fluctuation can be obtained which allow
us to determine the spin density energy in terms of the COBE data for
temperature fluctuations.Comment: Latex file 8K
Zero-point energy of massless scalar fields in the presence of soft and semihard boundaries in D dimensions
The renormalized energy density of a massless scalar field defined in a
D-dimensional flat spacetime is computed in the presence of "soft" and
"semihard" boundaries, modeled by some smoothly increasing potential functions.
The sign of the renormalized energy densities for these different confining
situations is investigated. The dependence of this energy on for the cases
of "hard" and "soft/semihard" boundaries are compared.Comment: 36 pages, LaTeX, 4 figure
Exposure to violence and PTSD symptoms among Somali women
Posttraumatic stress disorder (PTSD) symptoms, exposure to traumatic stressors, and health care utilization were examined in 84 women attending a primary health care clinic in Mogadishu, Somalia. The Somalia-Posttraumatic Diagnostic Scale was used in this active warzone to measure symptoms. Nearly all women reported high levels of confrontations with violence; half described being exposed to a potentially traumatizing event. Nearly one third had significant PTSD symptoms. Compared to those who did not, women who reported exposure to a traumatic stressor reported more confrontations with violence (7.1 vs. 3.3; p < . 001), health complaints (3.8 vs. 2.9; p = .03), and nearly 3 times as much (p = .03) health service utilization. A potentially traumatizing event was found to be a simplified proxy for assessing mental health distress in women attending a primary health care facility in highly insecure, unpredictable, resource-limited settings
Canonical Quantization of Interacting WZW Theories
Using canonical quantization we find the Virasoro centre for a class of
conformally-invariant interacting Wess-Zumino-Witten theories. The theories
have a group structure similar to that of Toda theories (both abelian and
non-abelian) but the usual Toda constraints on the coupling constants are
relaxed and the theories are not necessarily integrable. The general formula
for the Virasoro centre is compared to that derived by BRST methods in the Toda
case, and helps to explain the structure of the latter
Recommended from our members
New emissive mononuclear copper (I) complex: Structural and photophysical characterization focusing on solvatochromism, rigidochromism and oxygen sensing in mesoporous solid matrix
Gravitons and Lightcone Fluctuations
Gravitons in a squeezed vacuum state, the natural result of quantum creation
in the early universe or by black holes, will introduce metric fluctuations.
These metric fluctuations will introduce fluctuations of the lightcone. It is
shown that when the various two-point functions of a quantized field are
averaged over the metric fluctuations, the lightcone singularity disappears for
distinct points. The metric averaged functions remain singular in the limit of
coincident points. The metric averaged retarded Green's function for a massless
field becomes a Gaussian which is nonzero both inside and outside of the
classical lightcone. This implies some photons propagate faster than the
classical light speed, whereas others propagate slower. The possible effects of
metric fluctuations upon one-loop quantum processes are discussed and
illustrated by the calculation of the one-loop electron self-energy.Comment: 18pp, LATEX, TUTP-94-1
- âŠ