286 research outputs found
Collisional Damping of Giant Monopole and Quadrupole Resonances
Collisional damping widths of giant monopole and quadrupole excitations for
Sn and Pb at zero and finite temperatures are calculated within
Thomas-Fermi approximation by employing the microscopic in-medium
cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny
forces, and are compared with each other. The results for the collisional
widths of giant monopole and quadrupole vibrations at zero temperature as a
function of the mass number show that the collisional damping of giant monopole
vibrations accounts for about 30-40% of the observed widths at zero
temperature, while for giant quadrupole vibrations it accounts for only 20-30%
of the observed widths of zero temperature.Comment: RevTex, 12 pages, 6 PS figure
Collisional Effects in Isovector Response Function of Nuclear Matter at Finite Temperature
The dipole response function of nuclear matter at zero and finite
temperatures is investigated by employing the linearized version of the
extended TDHF theory with a non-Markovian binary collision term. Calculations
are carried out for nuclear dipole vibrations by employing the
Steinwedel-Jensen model and compared with experimental results for
and .Comment: 14 pages, RevTex, 3 PS figure
On growth of spinodal instabilities in nuclear matter-II:asymmetric matter
As an extension of our previous work, the growth of density fluctuations in
the spinodal region of charge asymmetric nuclear matter is investigated in the
basis of the stochastic mean-field approach in the non-relativistic framework.
A complete treatment of density correlation functions are presented by
including collective modes and non-collective modes as well.Comment: 20 pages, 6 figures, Accepted by Physical Review
Medium- and large-scale characterization of UMTS-allocated frequency division duplex channels
A dual-band sounder is used in both trolley and van measurements in the dense urban environment of Manchester city center to characterize the uplink (1920-1980 MHz) and downlink (2110-2170 MHz) frequency-division duplex (FDD) channels allocated to third-generation (3G) mobile radio systems. The data are analyzed with 60- and 5-MHz resolutions, as used for 3G wideband code-division multiple-access systems. Root-mean-square (rms) delay spread and 15-dB widths of mainly temporally averaged delay profile are presented either as cumulative distribution functions (cdfs) for each individual frequency band or as histograms of the difference between uplink and downlink on a local area basis. It was found that the histograms show larger differences between the two bands than the individual cdf and that the differences between the FDD channels are more pronounced on circumferential routes and shadowed locations. Correlations of rms delay spread with excess path loss and distance are on the order of 0.5 and 0.4, respectively
Quantal description of nucleon exchange in stochastic mean-field approach
Nucleon exchange mechanism is investigated in central collisions of symmetric
heavy-ions in the basis of the stochastic mean-field approach. Quantal
diffusion coefficients for nucleon exchange are calculated by including
non-Markovian effects and shell structure. Variances of fragment mass
distributions are calculated in central collisions of Ca +
Ca, Ca + Ca and Ni + Ni systems
Higher meson resonances in and
The role of higher meson resonances with spin 1 and 2 is investigated
quantitatively in the decay processes of and
. Among the higher resonances, we find that the
tensor meson can give a nontrivial contribution especially to the
decay process. When the contribution is
combined with the processes involving the vector and scalar meson intermediate
states, a good agreement with the recent measurements is achieved for both
decays. The effect of the is found to be sizable at the
intermediate photon energies and may be verified by precise measurements of the
recoil photon spectrum of the decay. The
dependence of the decay widths on various models for the - mixing
in the literature is also investigated.Comment: 16 pages, REVTeX, 6 figures, revised version, to appear in Phys. Rev.
Spinodal Instabilities in Nuclear Matter in a Stochastic Relativistic Mean-Field Approach
Spinodal instabilities and early growth of baryon density fluctuations in
symmetric nuclear matter are investigated in the basis of stochastic extension
of relativistic mean-field approach in the semi-classical approximation.
Calculations are compared with the results of non-relativistic calculations
based on Skyrme-type effective interactions under similar conditions. A
qualitative difference appears in the unstable response of the system: the
system exhibits most unstable behavior at higher baryon densities around
in the relativistic approach while most unstable
behavior occurs at lower baryon densities around in
the non-relativistic calculationsComment: 18 pages, 7 figure
Sigma-meson and omega-rho mixing effects in omega --> pi^+ pi^- gamma decay
We calculate the branching ratio of omega --> pi^+ pi^- gamma decay in a
phenomenological framework in which the contributions of VMD, chiral loops,
sigma-meson intermediate state amplitudes and the effects of omega-rho mixing
are considered. We conclude that the sigma-meson intermediate state amplitude
and omega-rho mixing make substantial contribution to the branching ratio.Comment: 10 pages RevTex, 4 Figures, to be published in Acta Phys. Pol.
Investigations of spinodal dynamics in asymmetric nuclear matter within a stochastic relativistic model
Cataloged from PDF version of article.Early development of spinodal instabilities and density correlation functions in asymmetric nuclear matter are investigated in the stochastic extension of the Walecka-type relativistic mean field including coupling with rho meson. Calculations are performed under typical conditions encountered in heavy-ion collisions and in the crusts of neutron stars. In general, growth of instabilities occur relatively slower for increasing charge asymmetry of matter. At higher densities around rho = 0.4 rho(0) fluctuations grow relatively faster in the quantal description than those found in the semi-classical limit. Typical sizes of early condensation regions extracted from density correlation functions are consistent with those found from dispersion relations of the unstable collective modes
Scalar mesons in radiative \phi\to K^0\bar{K}^0\gamma decay
We study the radiative decay within a
phenomenological framework by considering the contributions of the
and scalar resonances. We calculate the branching ratio by employing the coupling constants
and as determined by different experimental groups.Comment: 10 pages, 3 figure
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