102 research outputs found
Partial dynamical symmetry as a selection criterion for many-body interactions
We propose the use of partial dynamical symmetry (PDS) as a selection
criterion for higher-order terms in situations when a prescribed symmetry is
obeyed by some states and is strongly broken in others. The procedure is
demonstrated in a first systematic classification of many-body interactions
with SU(3) PDS that can improve the description of deformed nuclei. As an
example, the triaxial features of the nucleus 156Gd are analyzed.Comment: 5 pages, 3 figures, Phys. Rev. C, in pres
Partial Dynamical Symmetry in the Symplectic Shell Model
We present an example of a partial dynamical symmetry (PDS) in an interacting
fermion system and demonstrate the close relationship of the associated
Hamiltonians with a realistic quadrupole-quadrupole interaction, thus shedding
new light on this important interaction. Specifically, in the framework of the
symplectic shell model of nuclei, we prove the existence of a family of
fermionic Hamiltonians with partial SU(3) symmetry. We outline the construction
process for the PDS eigenstates with good symmetry and give analytic
expressions for the energies of these states and E2 transition strengths
between them. Characteristics of both pure and mixed-symmetry PDS eigenstates
are discussed and the resulting spectra and transition strengths are compared
to those of real nuclei. The PDS concept is shown to be relevant to the
description of prolate, oblate, as well as triaxially deformed nuclei.
Similarities and differences between the fermion case and the previously
established partial SU(3) symmetry in the Interacting Boson Model are
considered.Comment: 9 figure
An intrinsic state for an extended version of the interacting boson model
An intrinsic-state formalism for IBM-4 is presented. A basis of deformed
bosons is introduced which allows the construction of a general trial wave
function which has Wigner's spin-isospin SU(4) symmetry as a particular limit.
Intrinsic-state calculations are compared with exact ones showing good
agreement.Comment: 12 pages, TeX (ReVTeX). Content changed. Accepted in Phys. Rev.
Consistent description of magnetic dipole properties in transitional nuclei
It is shown that a consistent description of magnetic dipole properties in
transitional nuclei can be obtained in the interacting boson model-2 by F-spin
breaking mechanism, which is associated with differences between the proton and
neutron deformations. In particular, the long standing anomalies observed in
the -factors of the Os-Pt isotopes are resolved by a proper inclusion of
F-spin breaking.Comment: Revtex, 10 pages, 4 figures (available from authors upon request
Partial dynamical symmetry in quantum Hamiltonians with higher-order terms
A generic procedure is proposed to construct many-body quantum Hamiltonians
with partial dynamical symmetry. It is based on a tensor decomposition of the
Hamiltonian and allows the construction of a hierarchy of interactions that
have selected classes of solvable states. The method is illustrated in the
SO(6) limit of the interacting boson model of atomic nuclei and applied to the
nucleus Pt
Magnetic Dipole Sum Rules for Odd-Mass Nuclei
Sum rules for the total- and scissors-mode M1 strength in odd-A nuclei are
derived within the single-j interacting boson-fermion model. We discuss the
physical content and geometric interpretation of these sum rules and apply them
to ^{167}Er and ^{161}Dy. We find consistency with the former measurements but
not with the latter.Comment: 13 pages, Revtex, 1 figure, Phys. Rev. Lett. in pres
Sensitivity of tensor analyzing power in the process to the longitudinal isoscalar form factor of the Roper resonance electroexcitation
The tensor analyzing power of the process , for forward
deuteron scattering in the momentum interval 3.7 to 9 GeV/c, is studied in the
framework of exchange in an algebraic collective model for the
electroexcitation of nucleon resonances. We point out a special sensitivity of
the tensor analyzing power to the isoscalar longitudinal form factor of the
Roper resonance excitation. The main argument is that the ,
and resonances have only isovector longitudinal
form factors. It is the longitudinal form factor of the Roper excitation, which
plays an important role in the dependence of the tensor analyzing power. We
discuss possible evidence of swelling of hadrons with increasing excitation
energy.Comment: 12 pages, 10 figure
Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei
A generalized M1 sum rule for orbital magnetic dipole strength from excited
symmetric states to mixed-symmetry states is considered within the
proton-neutron interacting boson model of even-even nuclei. Analytic
expressions for the dominant terms in the B(M1) transition rates from the first
and second states are derived in the U(5) and SO(6) dynamic symmetry
limits of the model, and the applicability of a sum rule approach is examined
at and in-between these limits. Lastly, the sum rule is applied to the new data
on mixed-symmetry states of 94Mo and a quadrupole d-boson ratio
is obtained in a largely
parameter-independent wayComment: 19 pages, 3 figures, Revte
Test of Nuclear Wave Functions for Pseudospin Symmetry
Using the fact that pseudospin is an approximate symmetry of the Dirac
Hamiltonian with realistic scalar and vector mean fields, we derive the wave
functions of the pseudospin partners of eigenstates of a realistic Dirac
Hamiltonian and compare these wave functions with the wave functions of the
Dirac eigenstates.Comment: 11 pages, 4 figures, minor changes in text and figures to conform
with PRL requirement
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