4,441 research outputs found
T=0 Neutron-Proton Correlations at High Angular Momenta
The properties of T=0 neutron-proton correlations are discussed within the
frame work of different model calculations. Single-j shell calculations reveal
that the T=0 correlations remain up to the highest frequencies. They are more
complex and cannot be restricted to L=0 pairs only. Whereas it may be difficult
to find clear evidence for T=0 pairing at low spins, T=0 correlations are found
to induce a new excitation scheme at high angular momenta.Comment: 9 pages, 5 figure
Properties of N=90 Isotones within the Mean Field Perspective
In recent years, the N=90 isotones have been investigated to a large extent
in relation to studies of quantum phase transitions. In this paper, we use the
mean field approach with pairing-deformation self consistent Total Routhian
Surface (TRS) calculations to study the N=90 isotones and neigh- bouring
nuclei. The important probes, such as moments of inertia, quadrupole moments,
the energy ratio of E(4+1)/E(2+1), octupole and hexadecapole degrees of freedom
are considered and the cal- culated results are compared with the available
experimental data. From a microscopic point of view, the N=90 isotones
characterize the onset of the deformed region and are very well described by
mean field calculations. The results are compared with those from other studies
in beyond mean-field approximations. Shape coexistence phenomena in the region
of interest are discussed.Comment: 7 pages, 10 figure
Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati Equations
An operator Riccati equation from systems theory is considered in the case
that all entries of the associated Hamiltonian are unbounded. Using a certain
dichotomy property of the Hamiltonian and its symmetry with respect to two
different indefinite inner products, we prove the existence of nonnegative and
nonpositive solutions of the Riccati equation. Moreover, conditions for the
boundedness and uniqueness of these solutions are established.Comment: 31 pages, 3 figures; proof of uniqueness of solutions added; to
appear in Journal of Evolution Equation
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