175 research outputs found
Manifestation of three-body forces in f7/2-shell nuclei
The traditional nuclear shell model approach is extended to include many-body
forces. The empirical Hamiltonian with a three-body force is constructed for
the identical nucleons on the 0f7/2 shell. Manifestations of the three-body
force in spectra, binding energies, seniority mixing, particle-hole symmetry,
electromagnetic and particle transition rates are investigated. It is shown
that in addition to the usual expansion of the valence space within the
tranditional two-body shell model, the three-body component in the Hamiltonian
can be an important part improving the quality of the theoretical approach.Comment: 5 pages, 1 figur
Neutron Resonance Widths and the Porter-Thomas Distribution
Experimental evidence has recently put the validity of the Porter-Thomas
distribution (PTD) for partial neutron widths into question. We identify two
terms in the effective Hamiltonian that violate orthogonal invariance (the
basis for the PTD). Both are due to the coupling to the decay channels. We show
that realistic estimates for the coupling to the neutron channel and for
non-statistical gamma decays yield significant modifications of the PTD.Comment: 5 pages, 2 figure
"Super-radiance" and the width of exotic baryons
It is suggested that the narrow width of the recently observed resonance
with strangeness could be a result of the
super-radiance mechanism of the redistribution of the widths of overlapping
resonances due to their coupling through common decay channels.Comment: This is an update of the original version submitted on October 08,
2003; it includes consideration of an additional model and one new figur
Effective three-body interactions in nuclei
It is shown that the three-body forces in the shell, for which
recently evidence was found on the basis of spectroscopic properties of the Ca
isotopes and isotones, can be most naturally explained as an effective
interaction due to excluded higher-lying shells, in particular the
orbit.}Comment: 5 pages, 1 tables, accepted for publication in Europhysics Letter
Nuclear pairing and Coriolis effects in proton emitters
We introduce a Hartree-Fock-Bogoliubov mean-field approach to treat the
problem of proton emission from a deformed nucleus. By substituting a rigid
rotor in a particle-rotor-model with a mean-field we obtain a better
description of experimental data in Ho. The approach also elucidates
the softening of kinematic coupling between particle and collective rotation,
the Coriolis attenuation problem.Comment: 2 pages, 1 figur
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