8,583 research outputs found
Dimensional reduction in QCD: Lessons from lower dimensions
In this contribution we present the results of a series of investigations of
dimensional reduction, applied to SU(3) gauge theory in 2 + 1 dimensions. We
review earlier results, present a new reduced model with Z(3) symmetry, and
discuss the results of numerical simulations of this model.Comment: 10 pages, Talk given at Workshop on Finite Density QCD, Nara Japan
10-12 Jul 200
Turbulent kinetic energy equation and free mixing
Calculation of free shear flows was carried out to investigate the usefulness of several concepts which were previously successfully applied to wall flows. The method belongs to the class of differential approaches. The turbulence is taken into account by the introduction of one additional partial differential equation, the transport equation for the turbulent shear stress. The structure of turbulence is modeled after Bradshaw et al. This model was used successfully in boundary layers and its applicability to other flows is demonstrated. The work reported differs substantially from that of an earlier attempt to use this approach for calculation of free flows. The most important difference is that the region around the center line is treated by invoking the interaction hypothesis (concerning the structure of turbulence in the regions separated by the velocity extrema). The compressibility effects on shear layer spreading at low and moderate Mach numbers were investigated. In the absence of detailed experiments in free flows, the evidence from boundary layers that at low Mach numbers the structure of turbulence is unaffected by the compressibility was relied on. The present model was tested over a range of self-preserving and developing flows including pressure gradients using identical empirical input. The dependence of the structure of turbulence on the spreading rate of the shear layer was established
Z(3) Symmetric Dimensional Reduction of (2+1)D QCD
Here we present a candidate for a Z(3)-symmetric reduced action for the
description of the (2+1)D SU(3) gauge theoryComment: 2 pages, Statistical QCD pro
Modification of nuclear transitions in stellar plasma by electronic processes: K-isomers in 176Lu and 180Ta under s-process conditions
The influence of the stellar plasma on the production and destruction of
K-isomers is studied for the examples 176Lu and 180Ta. Individual
electromagnetic transitions are enhanced predominantly by nuclear excitation by
electron capture, whereas the other mechanisms of electron scattering and
nuclear excitation by electron transition give only minor contributions. It is
found that individual transitions can be enhanced significantly for low
transition energies below 100 keV. Transitions with higher energies above 200
keV are practically not affected. Although one low-energy transition in 180Ta
is enhanced by up to a factor of 10, the stellar transition rates from low-K to
high-K states via so-called intermediate states in 176Lu and 180Ta do not
change significantly under s-process conditions. The s-process nucleosynthesis
of 176Lu and 180Ta remains essentially unchanged.Comment: 10 pages, 10 figures, Phys. Rev. C, accepte
Hubbard Model with Luscher fermions
First applications of the new algorithm simulating dynamical fermions are
reported. The method reproduces previous results obtained with different
techniques.Comment: talk presented at the XII International Symposium LATTICE94,
Bielefeld, Germany, September 1994, to appear in the Proceedings. 3 pages,
LATEX, required Elsevier espcrc2.sty style file is attached at the end of
this LATEX text. Postscript figures included in the latex document with the
epsf facilit
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