765 research outputs found
Stochastic approach to correlations beyond the mean field with the Skyrme interaction
Large-scale calculation based on the multi-configuration Skyrme density
functional theory is performed for the light N=Z even-even nucleus, 12C.
Stochastic procedures and the imaginary-time evolution are utilized to prepare
many Slater determinants. Each state is projected on eigenstates of parity and
angular momentum. Then, performing the configuration mixing calculation with
the Skyrme Hamiltonian, we obtain low-lying energy-eigenstates and their
explicit wave functions. The generated wave functions are completely free from
any assumption and symmetry restriction. Excitation spectra and transition
probabilities are well reproduced, not only for the ground-state band, but for
negative-parity excited states and the Hoyle state.Comment: 4 pages, 1 figure, Talk at 2nd International Nuclear Physics
Conference "Nuclear Structure and Dynamics", Opatija, Croatia, July 9 - 13,
201
Imaginary-time method for radiative capture reaction rate
We propose a new computational method for astrophysical reaction rate of
radiative capture process. In the method, an evolution of a wave function is
calculated along the imaginary-time axis which is identified as the inverse
temperature. It enables direct evaluation of reaction rate as a function of
temperature without solving any scattering problem. The method is tested for
two-body radiative capture reaction, , showing that it gives identical results to that calculated by the
ordinary procedure. The new method will be suited for calculation of
triple-alpha radiative capture rate for which an explicit construction of the
scattering solution is difficult.Comment: 8 pages, 7 figure
Multi-cluster dynamics in and analogy to clustering in
We investigate structure of and discuss the difference
and similarity between the structures of and by answering the questions if the linear-chain and gaslike cluster states,
which are proposed to appear in , survives, or new structure
states appear or not. We introduce a microscopic cluster model called,
Hyper-Tohsaki-Horiuchi-Schuck-R\"opke (H-THSR) wave function, which is an
extended version of the THSR wave function so as to describe
hypernuclei. We obtained two bound states and two resonance (quasi-bound)
states for in , corresponding to the four
states in . However, the inversion of level ordering
between the spectra of and , i.e. that the
and states in correspond to the
and states in , respectively, is shown to occur. The
additional particle reduces sizes of the and states
in very much, but the shrinkage of the state is
only a half of the other states. In conclusion, the Hoyle state becomes quite a
compact object with configuration in
and is no more gaslike state composed of the
clusters. Instead, the state in , coming from the
state, appears as a gaslike state composed of
configuration, i.e. the Hoyle analog
state. A linear-chain state in a hypernucleus is for the first time
predicted to exist as the state in with more
shrunk arrangement of the clusters along -axis than the
linear-chain configuration realized in the state.Comment: 9 pages, 6 figures, figures rearranged, accepted for publication in
PL
Monopole Excitation to Cluster States
We discuss strength of monopole excitation of the ground state to cluster
states in light nuclei. We clarify that the monopole excitation to cluster
states is in general strong as to be comparable with the single particle
strength and shares an appreciable portion of the sum rule value in spite of
large difference of the structure between the cluster state and the
shell-model-like ground state. We argue that the essential reasons of the large
strength are twofold. One is the fact that the clustering degree of freedom is
possessed even by simple shell model wave functions. The detailed feature of
this fact is described by the so-called Bayman-Bohr theorem which tells us that
SU(3) shell model wave function is equivalent to cluster model wave function.
The other is the ground state correlation induced by the activation of the
cluster degrees of freedom described by the Bayman-Bohr theorem. We
demonstrate, by deriving analytical expressions of monopole matrix elements,
that the order of magnitude of the monopole strength is governed by the first
reason, while the second reason plays a sufficient role in reproducing the data
up to the factor of magnitude of the monopole strength. Our explanation is made
by analysing three examples which are the monopole excitations to the
and states in O and the one to the state in C.
The present results imply that the measurement of strong monopole transitions
or excitations is in general very useful for the study of cluster states.Comment: 11 pages, 1 figure: revised versio
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