441 research outputs found
Linear response theory in the continuum for deformed nuclei: Green's function vs. time-dependent Hartree-Fock with the absorbing-boundary condition
The continuum random-phase approximation is extended to the one applicable to
deformed nuclei. We propose two different approaches. One is based on the use
of the three dimensional (3D) Green's function and the other is the
small-amplitude TDHF with the absorbing-boundary condition. Both methods are
based on the 3D Cartesian grid representation and applicable to systems without
any symmetry on nuclear shape. The accuracy and identity of these two methods
are examined with the BKN interaction. Using the full Skyrme energy functional
in the small-amplitude TDHF approach, we study the isovector giant dipole
states in the continuum for O-16 and for even-even Be isotopes.Comment: 15 pages, 8 figure
Removal of Spurious Admixture in a Self-consistent Theory of Adiabatic Large Amplitude Collective Motion
In this article we analyse, for a simple model, the properties of a practical
implementation of a fully self-consistent theory of adiabatic large-amplitude
collective motion using the local harmonic approach. We show how we can deal
with contaminations arising from spurious modes, caused by standard simplifying
approximations. This is done both at zero and finite angular momentum. We
analyse in detail the nature of the collective coordinate in regions where they
cross spurious modes and mixing is largest
Adiabatic Selfconsistent Collective Coordinate Method for Large Amplitude Collective Motion in Superconducting Nuclei
An adiabatic approximation to the selfconsistent collective coordinate method
is formulated in order to describe large amplitude collective motions in
superconducting nuclei on the basis of the time-dependent
Hartree-Fock-Bogoliubov equations of motion. The basic equations are presented
in a local harmonic form which can be solved in a similar way as the
quasiparticle RPA equations. The formalism guarantees the conservation of
nucleon number expectation values. An extension to the multi-dimensional case
is also discussed
Application of the Adiabatic Selfconsistent-Collective-Coordinate Method to a Solvable Model of Prolate-Oblate Shape Coexistence
The adiabatic selfconsistent collective coordinate method is applied to an
exactly solvable multi-O(4) model which simulates nuclear shape coexistence
phenomena. Collective mass and dynamics of large amplitude collective motions
in this model system are analysed, and it is shown that the method can well
describe the tunneling motions through the barrier between the prolate and
oblate local minima in the collective potential. Emergence of the doublet
pattern is well reproduced.Comment: 25 pages including 9 figure
Collective Paths Connecting the Oblate and Prolate Shapes in 68Se and 72Kr Suggested by the Adiabatic Self-Consistent Collective Coordinate Method
By means of the adiabatic self-consistent collective coordinate method and
the pairing-plus-quadrupole interaction, we have obtained the self-consistent
collective path connecting the oblate and prolate local minima in 68Se and 72Kr
for the first time. The self-consistent collective path is found to run
approximately along the valley connecting the oblate and prolate local minima
in the collective potential energy landscape. This result of calculation
clearly indicates the importance of triaxial deformation dynamics in
oblate-prolate shape coexistence phenomena.Comment: 24 pages including 5 figure
N-Body Nuclear Forces at Short Distances in Holographic QCD
We provide a calculation of N-body (N>2) nucleon interactions at short
distances in holographic QCD. In the Sakai-Sugimoto model of large N_c massless
QCD, N baryons are described by N Yang-Mills instantons in 5 spacetime
dimensions. We compute a classical short distance interaction hamiltonian for N
'tHooft instantons. This corresponds to N baryons sharing identical classical
spins and isospins. We find that genuine N-body nuclear forces turn out to
vanish for N>2, at the leading order. This suggests that classical N-body
forces are always suppressed compared with 2-body forces.Comment: 4 page
Dipole responses in Nd and Sm isotopes with shape transitions
Photoabsorption cross sections of Nd and Sm isotopes from spherical to
deformed even nuclei are systematically investigated by means of the
quasiparticle-random-phase approximation based on the Hartree-Fock-Bogoliubov
ground states (HFB+QRPA) using the Skyrme energy density functional. The
gradual onset of deformation in the ground states as increasing the neutron
number leads to characteristic features of the shape phase transition. The
calculation well reproduce the isotopic dependence of broadening and emergence
of a double-peak structure in the cross sections without any adjustable
parameter. We also find that the deformation plays a significant role for
low-energy dipole strengths. The strengths are fragmented and considerably
lowered in energy. The summed strength up to 10 MeV is enhanced by a
factor of five or more.Comment: 5 pages including 6 figure
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