Local energy-density functional approach to many-body nuclear systems with s-wave pairing

The ground-state properties of superfluid nuclear systems with ^1S_0 pairing are studied within a local energy-density functional (LEDF) approach. A new form of the LEDF is proposed with a volume part which fits the Friedman- Pandharipande and Wiringa-Fiks-Fabrocini equation of state at low and moderate densities and allows an extrapolation to higher densities preserving causality. For inhomogeneous systems, a surface term with two free parameters is added. In addition to the Coulomb direct and exchange interaction energy, an effective density-dependent Coulomb-nuclear correlation term is included with one more free parameter, giving a contribution of the same order of magnitude as the Nolen-Schiffer anomaly in Coulomb displacement energy. The root-mean-square deviations from experimental masses and radii with the proposed LEDF come out about a factor of two smaller than those obtained with the conventional functionals based on the Skyrme or finite-range Gogny force, or on the relativistic mean-field theory. The generalized variational principle is formulated leading to the self-consistent Gor'kov equations which are solved exactly, with physical boundary conditions both for the bound and scattering states. With a zero-range density-dependent cutoff pairing interaction incorporating a density-gradient term, the evolution of differential observables such as odd-even mass differences and staggering in charge radii, is reproduced reasonably well, including kinks at magic neutron numbers. An extrapolation to infinite nuclear matter is discussed. We study also the dilute limit in both the weak and strong coupling regime.Comment: 19 pages, 8 figures. LaTeX, with modified cls file supplied. To be published in vol. 3 of the series "Advances in Quantum Many-Body Theory", World Scientific (Proceedings of the MBX Conference, Seattle, September 10-15, 1999

Influence of 2p-2h configurations on beta-decay rates

The effects of the phonon-phonon coupling on the beta-decay rates of neutron-rich nuclei are studied in a microscopic model based on Skyrme-type interactions. The approach uses a finite-rank separable approximation of the Skyrme-type particle-hole (p-h) residual interaction. Very large two-quasiparticle spaces can thus be treated. A redistribution of the Gamow-Teller (G-T) strength is found due to the tensor correlations and the 2p-2h fragmentation of G-T states. As a result, the beta-decay half-lives are decreased significantly. Using the Skyrme interaction SGII together with a volume-type pairing interaction we illustrate this reduction effect by comparing with available experimental data for the Ni isotopes and neutron-rich N=50 isotones. We give predictions for 76Fe and 80Ni in comparison with the case of the doubly-magic nucleus 78Ni which is an important waiting point in the r-process.Comment: 8 pages, 6 figures, accepted for publication in Physical Review

ABOUT THE LABORATORY DIAGNOSTICS OF SEVERE ACUTE RESPIRATORY SYNDROME AT PRIMORSKIJ TERRITORY

The difficulties of SARS laboratory diagnosis, which took place at Primorski Territory during first months of this dangerous infection epidemic are shown

Coherent states associated to the wavefunctions and the spectrum of the isotonic oscillator

Classes of coherent states are presented by replacing the labeling parameter $z$ of Klauder-Perelomov type coherent states by confluent hypergeometric functions with specific parameters. Temporally stable coherent states for the isotonic oscillator Hamiltonian are presented and these states are identified as a particular case of the so-called Mittag-Leffler coherent states.Comment: 12 page

Theoretical Aspects of Science with Radioactive Nuclear Beams

Physics of radioactive nuclear beams is one of the main frontiers of nuclear science today. Experimentally, thanks to technological developments, we are on the verge of invading the territory of extreme N/Z ratios in an unprecedented way. Theoretically, nuclear exotica represent a formidable challenge for the nuclear many-body theories and their power to predict nuclear properties in nuclear terra incognita. It is important to remember that the lesson learned by going to the limits of the nuclear binding is also important for normal nuclei from the neighborhood of the beta stability valley. And, of course, radioactive nuclei are crucial astrophysically; they pave the highway along which the nuclear material is transported up in the proton and neutron numbers during the complicated synthesis process in stars.Comment: 26 ReVTeX pages, 11 Postscript figures, uses epsf.sty, to be published in: Theme Issue on Science with Beams of Radioactive Nuclei, Philosophical Transactions, ed. by W. Gelletl

Unified (q;α,β,γ;ν)(q;\alpha,\beta,\gamma;\nu)-deformation of one-parametric q-deformed oscillator algebras

We define a generalized $(q;\alpha,\beta,\gamma;\nu)$-deformed oscillator algebra and study the number of its characteristics. We describe the structure function of deformation, analyze the classification of irreducible representations and discuss the asymptotic spectrum behaviour of the Hamiltonian. For a special choice of the deformation parameters we construct the deformed oscillator with discrete spectrum of its "quantized coordinate" operator. We establish its connection with the (generalized) discrete Hermite I polynomials

MLVA-TYPINGIN THE ANALYSIS of THE POPULATION STRUCTURE of VIBRIO CHOLERAE, CIRCULATING IN PRIMORSKY KRAI TERRITORY, DURING EPIDEMIOLOGICAL WELFARE

In order to study the population structure of Vibrio cholerae, circulating in the waters of Primorsky Region territory during epidemiological welfare, was carried out a retrospective MLVA-typing of 50 V.cholerae strains isolated since 1976 up to 2011 years. There was revealed non-toxigenic V. cholerae strains heterogeneity, consisting in the variability of structure of these tandem repeat loci. The waters circulation of Primorsky Region territory during epidemiological welfare V.cholerae, submitted by no less than 30 unique genotypes and 8 clusters is represented. There is a high discriminatory power of the MLVA. The Hunter Gaston index of isolates studied is 0.988. In some cases, was revealed relationship between genotype (identical and closely related allelic profiles) with time and place of V.cholerae strains isolation

Negative Kaons in Dense Baryonic Matter

Kaon polarization operator in dense baryonic matter of arbitrary isotopic composition is calculated including s- and p-wave kaon-baryon interactions. The regular part of the polarization operator is extracted from the realistic kaon-nucleon interaction based on the chiral and 1/N_c expansion. Contributions of the Lambda(1116), Sigma(1195), Sigma*(1385) resonances are taken explicitly into account in the pole and regular terms with inclusion of mean-field potentials. The baryon-baryon correlations are incorporated and fluctuation contributions are estimated. Results are applied for K- in neutron star matter. Within our model a second-order phase transition to the s-wave K- condensate state occurs at rho_c \gsim 4 \rho_0 once the baryon-baryon correlations are included. We show that the second-order phase transition to the p-wave $K^-$ condensate state may occur at densities $\rho_c \sim 3\div 5 \rho_0$ in dependence on the parameter choice. We demonstrate that a first-order phase transition to a proton-enriched (approximately isospin-symmetric) nucleon matter with a p-wave K- condensate can occur at smaller densities, \rho\lsim 2 \rho_0. The transition is accompanied by the suppression of hyperon concentrations.Comment: 41 pages, 24 figures, revtex4 styl

Reexamining Gamow-Teller decays near Ni 78

Decays of neutron-rich nuclei Zn82,83 and Ga82,83 produced in proton-induced fission of U238 were studied at the Holifield Radioactive Ion Beam Facility using on-line mass separation and β-γ spectroscopy techniques. New γ-ray transitions were identified and level schemes, which include states at high excitation energies in the range between 3-7 MeV were constructed. These high-energy levels were identified to be populated through allowed Gamow-Teller β transitions, and their structure was interpreted with new shell-model calculations. A β-delayed neutron branching ratio of 69±7% was deduced for Zn82 and revised β-decay half-life values of Zn82 [155(17)(20) ms] and Zn83 [122(28) ms] were determined