82 research outputs found
Tensor-optimized shell model for the Li isotopes with a bare nucleon-nucleon interaction
We study the Li isotopes systematically in terms of the tensor-optimized
shell model (TOSM) by using a bare nucleon-nucleon interaction as the AV8'
interaction. The short-range correlation is treated in the unitary correlation
operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role
of the tensor force on each spectrum of the Li isotopes. It is found that the
tensor force produces quite a characteristic effect on various states in each
spectrum and those spectra are affected considerably by the tensor force. The
energy difference between the spin-orbit partner, the p1/2 and p3/2 orbits of
the last neutron, in 5Li is caused by opposite roles of the tensor correlation.
In 6Li, the spin-triplet state in the LS coupling configuration is favored
energetically by the tensor force in comparison with jj coupling shell model
states. In 7,8,9Li, the low-lying states containing extra neutrons in the p3/2
orbit are favored energetically due to the large tensor contribution to allow
the excitation from the 0s orbit to the p1/2 orbit by the tensor force. Those
three nuclei show the jj coupling character in their ground states which is
different from 6Li.Comment: 12 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1108.393
Role of the tensor interaction in He isotopes with a tensor-optimized shell model
We studied the role of the tensor interaction in He isotopes systematically
on the basis of the tensor-optimized shell model (TOSM). We use a bare
nucleon-nucleon interaction AV8 obtained from nucleon-nucleon scattering data.
The short-range correlation is treated in the unitary correlation operator
method (UCOM). Using the TOSM+UCOM approach, we investigate the role of tensor
interaction on each spectrum in He isotopes. It is found that the tensor
interaction enhances the LS splitting energy observed in 5He, in which the p1/2
and p3/2 orbits play different roles on the tensor correlation. In {6,7,8}He,
the low-lying states containing extra neutrons in the p3/2 orbit gain the
tensor contribution. On the other hand, the excited states containing extra
neutrons in the p1/2 orbit lose the tensor contribution due to the
Pauli-blocking effect with the 2p2h states in the 4He core configuration.Comment: 11 pages, 8 figure
Shell evolution and nuclear forces
We present a quantitative study of the role played by different components
characterizing the nucleon-nucleon interaction in the evolution of the nuclear
shell structure. It is based on the spin-tensor decomposition of an effective
two-body shell-model interaction and the subsequent study of effective
single-particle energy variations in a series of isotopes or isotones. The
technique allows to separate unambiguously contributions of the central, vector
and tensor components of the realistic effective interaction. We show that
while the global variation of the single-particle energies is due to the
central component of the effective interaction, the characteristic behavior of
spin-orbit partners, noticed recently, is mainly due to its tensor part. Based
on the analysis of a well-fitted realistic interaction in sdpf-shell model
space, we analyze in detail the role played by the different terms in the
formation and/or disappearance of N=16, N=20 and N=28 shell gaps in
neutron-rich nuclei.Comment: 6 pages, 4 figure
Strangeness nuclear physics: a critical review on selected topics
Selected topics in strangeness nuclear physics are critically reviewed. This
includes production, structure and weak decay of --Hypernuclei, the
nuclear interaction and the possible existence of bound
states in nuclei. Perspectives for future studies on these issues are also
outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical
Journal
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