266 research outputs found
Four-body structure of Li and spin-dependent interaction
Two spin-doublet states of %- and - in
Li are studied on the basis of the
four-body model. We employ the two-body interactions which reproduce the
observed properties of any subsystems composed of ,
and , and . Furthermore, the
interaction is adjusted so as to reproduce the - splitting of in
H. The calculated energy splittings of - and
- states in Li are 0.69 MeV and 0.46 MeV, which are
in good agreement with the resent observed data. The spin-dependent components
of the interaction are discussed.Comment: 6 pages, 2 figures, published to be in Phys. Rev.
pi^- decay rates of p-shell hypernuclei revisited
Explicit expressions for the parity-violating s-wave and the
parity-conserving p-wave contributions to pi- weak-decay rates of Lambda
hypernuclei in the 1p shell are given in the weak-coupling limit, to update
previous shell-model calculations and to compare with recent pi- spectra and
total decay rates measured by the FINUDA Collaboration. A useful sum rule for
the summed strength of Lambda_{1s} --> pi- + proton_{1p} weak decays is
derived. Fair agreement between experiment and calculations is reached, using
the primary s-wave amplitude and Cohen-Kurath nuclear wavefunctions. The role
of the p-wave amplitude is studied in detail for Lambda-15N and found to be
secondary. Previous assignments of ground-state spin-parity values are
confirmed and a new assignment is made, spin-parity 3/2+ for Lambda-15N, based
on the substantial suppression calculated here for spin-parity 1/2+.Comment: published version; new footnote 2 added in proof; related to recent
FINUDA data, arXiv:0905.0623 [nucl-ex] submitted to Phys. Lett.
Relativistic Mean-Field and Beyond Approaches for Deformed Hypernuclei
We report the recent progress in relativistic mean-field (RMF) and beyond
approaches for the low-energy structure of deformed hypernuclei. We show that
the hyperon with orbital angular momentum (or )
generally reduces (enhances) nuclear quadrupole collectivity. The beyond
mean-field studies of hypernuclear low-lying states demonstrate that there is
generally a large configuration mixing between the two components and in the hypernuclear states. The mixing weight
increases as the collective correlation of nuclear core becomes stronger.
Finally, we show how the energies of hypernuclear low-lying states are
sensitive to parameters in the effective interaction, the
uncertainty of which has a large impact on the predicted maximal mass of
neutron stars.Comment: 12 pages, 7 figures. A plenary talk given at the 13th International
Conference on Hypernuclear and Strange Particle Physics, June 24-29, 2018,
Portsmouth, V
Disappearance of nuclear deformation in hypernuclei: a perspective from a beyond-mean-field study
The previous mean-field calculation [Myaing Thi Win and K. Hagino, Phys. Rev.
C{\bf 78}, 054311 (2008)] has shown that the oblate deformation in
Si disappears when a particle is added to these nuclei.
We here investigate this phenomenon by taking into account the effects beyond
the mean-field approximation. To this end, we employ the microscopic
particle-rotor model based on the covariant density functional theory. We show
that the deformation of Si does not completely disappear, even though it
is somewhat reduced, after a particle is added if the
beyond-mean-field effect is taken into account. We also discuss the impurity
effect of particle on the electric quadrupole transition, and show
that an addition of a particle leads to a reduction in the
value, as a consequence of the reduction in the deformation parameter.Comment: 6 pages, 5 figures. The version to appear in Phys. Rev.
Low-energy hypernuclear spectra within a microscopic particle-rotor model with a relativistic point-coupling hyperon-nucleon interaction
We extend the microscopic particle-rotor model for hypernuclear low-lying states by including the derivative and tensor coupling terms in the point-coupling nucleon- particle () interaction. Taking C as an example, we show that a good overall description for excitation spectra is achieved with four sets of effective interaction. We find that the hyperon binding energy decreases monotonically with increasing the strengths of the high-order interaction terms. In particular, the tensor coupling term decreases the energy splitting between the first and states and increases the energy splitting between the first and states in C
Light hypernuclei in four-body cluster models
Detailed structure calculations in Be, H,
Li, H and Li are performed
within the framework of the microscopic two-, three- and four-body cluster
models using the Gaussian Expansion Method.Comment: 14 pages, 19 figures. To be published in Phys. Rev.
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