26,311 research outputs found
Theoretical study of the decay-out spin of superdeformed bands in the Dy and Hg regions
Decay of the superdeformed bands have been studied mainly concentrating upon
the decay-out spin, which is sensitive to the tunneling probability between the
super- and normal-deformed wells. Although the basic features are well
understood by the calculations, it is difficult to precisely reproduce the
decay-out spins in some cases. Comparison of the systematic calculations with
experimental data reveals that values of the calculated decay-out spins scatter
more broadly around the average value in both the 150 and 190
regions, which reflects the variety of calculated tunneling probability in each
band.Comment: 6 pages 4 figures (30 PS files). To appear in Proc. of NS2000
(Nuclear Structure 2000) conf., at MSU, 15-19 Aug., 200
Parameterizing individual effects of shear and stratification on mixing in stably stratified shear flows
This study proposes new parameterizations of diapycnal mixing by reanalyzing the results of previous laboratory and numerical experiments on homogeneous stably stratified shear flows. Unlike previous studies that use either the turbulent Froude number Fr or gradient Richardson number Ri(g), this study parameterizes nondimensional momentum and buoyancy fluxes as functions of Fr and a turbulent shear number Sh, in order to quantify individual effects of shear and stratification. Turbulent momentum flux is found to depend linearly on Sh and to decrease monotonically with decreasing Fr. Turbulent buoyancy flux has a peak at moderate Fr. With increasing Sh, it decreases and increases at high and low Fr, respectively. The increase of Sh also cause relatively small but significant decreases of nondimensional turbulent properties, such as the nondimensional conversion rate of turbulent potential energy to background potential energy. The proposed parameterizations lie within the scatter of limited available field data. The parameterizations may be reduced to Ri(g)-based ones by incorporating the relationship between Ri(g) and turbulence intensity observed in the field. Existing stability functions for two-equation turbulent closure schemes are found to over-predict mixing efficiency at low Fr
QED Radiative Corrections to the Non-annihilation Processes Using the Structure Function and the Parton Shower
Inclusion of the QED higher order radiative corrections in the two-photon
process, e+e- -> e+e- mu+mu-, is examined by means of the structure function
and the parton shower. Results are compared with the exact
calculations and give a good agreement. These two methods should be universally
applicable to any other non-annihilation processes like the single-W
productions in the e+e- collisions. In this case, however, the energy scale for
the evolution by the renormalization-group equation should be chosen properly
depending on the dominant diagrams for the given process. A method to find the
most suitable energy scale is proposed.Comment: 17 pages, LaTeX, 5 figure
- ā¦