43,025 research outputs found
Exploration of Resonant Continuum and Giant Resonance in the Relativistic Approach
Single-particle resonant-states in the continuum are determined by solving
scattering states of the Dirac equation with proper asymptotic conditions in
the relativistic mean field theory (RMF). The regular and irregular solutions
of the Dirac equation at a large radius where the nuclear potentials vanish are
relativistic Coulomb wave functions, which are calculated numerically.
Energies, widths and wave functions of single-particle resonance states in the
continuum for ^{120}Sn are studied in the RMF with the parameter set of NL3.
The isoscalar giant octupole resonance of ^{120}Sn is investigated in a fully
consistent relativistic random phase approximation. Comparing the results with
including full continuum states and only those single-particle resonances we
find that the contributions from those resonant-states dominate in the nuclear
giant resonant processes.Comment: 16 pages, 2 figure
WILL MARKET PRICES ENHANCE CHINESE AGRICULTURE?: A TEST OF REGIONAL COMPARATIVE ADVANTAGE
China is the world's largest producer and consumer of food. In the past, China's governmental policy advocated regional self-sufficiency in agricultural production, and it is generally believed that regional self-sufficiency was enforced at high economic cost. However, this changed with the 1979 economic reforms which encouraged some regional specialization. It is expected that there may be further shifts in regional production patterns and interregional trade flows. This article uses data on land productivity to test for regional comparative advantage, and it provides some empirical evidence on provincial comparative advantage in cotton versus grain production in China.Agricultural and Food Policy, International Relations/Trade,
High energy particle collisions near the bifurcation surface
We consider generic nonextremal stationary dirty black holes. It is shown
that in the vicinity of any bifurcation surface the energy of collision of two
particles in the centre of mass frame can grow unbound. This is a generic
property that, in particular, includes collisions near the inner black hole
horizon analyzed earlier by different methods. The similar results are also
valid for cosmological horizons. The case of the de Sitter metric is discussed.Comment: 13 pages. Section V on dS spacetime added. Typos corrected, title
slightly changed. Final versio
Stability of correlated electronic systems under the influence of the electron-phonon interaction
We have used an exact diagonalization technique to study the stability of the
-Holstein and Hubbard-Holstein models under the influence of the
electron-phonon interaction. Previous results have been obtained using
frozen-phonon technique or introducing only a few dynamical phonon modes due to
the large Hilbert space. To check these results we have done exact
diagonalization in a small cluster (four sites) including all the phonon modes
allowed by symmetry. We compare our results with those obtained by using the
adiabatic approximation.Comment: 10 pages, 2 Postscript figure
Mean-field solution of the parity-conserving kinetic phase transition in one dimension
A two-offspring branching annihilating random walk model, with finite
reaction rates, is studied in one-dimension. The model exhibits a transition
from an active to an absorbing phase, expected to belong to the
universality class embracing systems that possess two symmetric absorbing
states, which in one-dimensional systems, is in many cases equivalent to parity
conservation. The phase transition is studied analytically through a mean-field
like modification of the so-called {\it parity interval method}. The original
method of parity intervals allows for an exact analysis of the
diffusion-controlled limit of infinite reaction rate, where there is no active
phase and hence no phase transition. For finite rates, we obtain a surprisingly
good description of the transition which compares favorably with the outcome of
Monte Carlo simulations. This provides one of the first analytical attempts to
deal with the broadly studied DP2 universality class.Comment: 4 Figures. 9 Pages. revtex4. Some comments have been improve
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