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Nuclear Theory·nucl-th

Wednesday·September 9, 2015

7 papers—7 primary·0 cross-listed

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  1. 01

    [Submitted on 8 Sept 2015]

    Proton pygmy resonances: predictions for N=20 isotones

    Y. Kim🇰🇷 · P. Papakonstantinou🇰🇷

    We study theoretically the low-energy electric-dipole response of N=20 isotones. We present results from a quasiparticle random-phase approximation (QRPA) and a continuum random-phase approximation (CRPA), and we compare them with results for the mirror Z=20 nuclei. According to our analysis, enhanced E1 strength is expected energetically well below the giant dipole resonance in the proton-rich isotones. Large amounts of E1 strength in the asymmetric N=20 isotones are predicted, unlike their equally asymmetric Z=20 mirror nuclei, pointing unambiguously to the role of structural effects such as loose binding. A proton-skin oscillation could develop especially in 46Fe. The proper description of non localized threshold transitions and the nucleon effective mass in mean-field treatments may affect theoretical predictions. We call for systematic theoretical investigations to quantify the role bulk-matter properties, in anticipation of measurements of E1 transitions in proton-rich nuclei.

    Comments:
    10 pages, incl. 9 figures and 2 tables; v2: some rephrasing and clarifications, corrected Fig. 6
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02259 [pdf]
    EPJA(2016)·3 citations
  2. 02

    [Submitted on 8 Sept 2015]

    Indication of change of phase in high-multiplicity proton-proton events at LHC in String Percolation Model

    I. Bautista🇲🇽 · A. Fernandez Téllez🇲🇽 · Premomoy Ghosh🇮🇳

    We analyze high multiplicity proton-proton () collision data in the framework of the String Percolation Model (SPM) that has been successful in describing several phenomena of multiparticle production, including the signatures of recent discovery of strongly interacting partonic matter, the Quark Gluon Plasma (QGP), in relativistic heavy-ion collisions. Our study in terms of the ratio of shear viscosity and entropy density () and the (LQCD) predicted signature of QCD change of phase, in terms of effective number of degrees of freedom (), reiterates the possibility of strongly interacting collective medium in these events.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1509.02278 [pdf]
    PRD(2015)·32 citations
  3. 03

    [Submitted on 8 Sept 2015]

    Investigation of shape coexistence in 118-128Te isotopes

    H. Sabri · Z. Jahangiri · M. A. Mohammadi

    In this paper, we have considered the interplay between phase transitions and configuration mixing of intruder excitations in the 118-128Te isotopes. A transitional interacting boson model Hamiltonian in both IBM-1 and IBM-2 versions which are based on affine Lie Algebra are employed to describe the evolution from spherical to deformed gamma unstable shapes along the chain of Te isotopes. The excitation energies, B(E0) and B(E2) transition rates are rather well reproduced in comparison with experimental counterparts when the weight of SO(6) limit is increased in Hamiltonian. Also our results show obvious relations between the configuration mixing ratio and quadrupole, hexadecapole and hexacontatetrapole deformation values in this isotopic chain.

    Comments:
    30 pages, 5 figures, 12 TABLES. arXiv admin note: substantial text overlap with arXiv:1507.08035 by other authors
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02282 [pdf]
    NPA(2016)·22 citations
  4. 04

    [Submitted on 8 Sept 2015]

    Four-body dynamics in 6Li elastic scattering

    Shin Watanabe · Takuma Matsumoto · Kazuyuki Ogata · Masanobu Yahiro

    We analyze 6Li elastic scattering in a wide range of incident energies (Ein), assuming the n + p + alpha + target four-body model and solving the dynamics with the four-body version of the continuum-discretized coupled-channels method (CDCC). Four-body CDCC well reproduces the experimental data with no adjustable parameter for 6Li + 209Bi scattering at Ein = 24-50 MeV and 6Li + 208Pb scattering at Ein = 29-210 MeV. In the wide Ein range, 6Li breakup is significant and provides repulsive corrections to the folding potential. As an interesting property, d breakup is strongly suppressed in 6Li-breakup processes independently of Ein. We investigate what causes the d-breakup suppression.

    Comments:
    10 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02292 [pdf]
    PRC(2015)·15 citations
  5. 05

    [Submitted on 8 Sept 2015]

    Electric quadrupole and magnetic dipole moments of odd nuclei near the magic ones in a self-consistent approach

    G. Co' · V. De Donno · M. Anguiano · R. N. Bernard · A. M. Lallena

    We present a model which describes the properties of odd-even nuclei with one nucleon more, or less, with respect to the magic number. In addition to the effects related to the unpaired nucleon, we consider those produced by the excitation of the closed shell core. By using a single particle basis generated with Hartree-Fock calculations, we describe the polarization of the doubly magic-core with Random Phase Approximation collective wave functions. In every step of the calculation, and for all the nuclei considered, we use the same finite-range nucleon-nucleon interaction. We apply our model to the evaluation of electric quadrupole and magnetic dipole moments of odd-even nuclei around oxygen, calcium, zirconium, tin and lead isotopes. Our Random Phase Approximation description of the polarization of the core improves the agreement with experimental data with respect to the predictions of the independent particle model. We compare our results with those obtained in first-order perturbation theory, with those produced by Hartree-Fock-Bogolioubov calculations and with those generated within the Landau-Migdal theory of finite Fermi systems. The results of our universal, self-consistent, and parameter free approach have the same quality of those obtained with phenomenological approaches where the various terms of the nucleon-nucleon interaction are adapted to reproduce some specific experimental data. A critical discussion on the validity of the model is presented.

    Comments:
    18 pages, 7 figures, 7 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02321 [pdf]
    PRC(2015)·19 citations
  6. 06

    [Submitted on 8 Sept 2015]

    Multipole modes in deformed nuclei within the finite amplitude method

    M. Kortelainen · N. Hinohara · W. Nazarewicz

    Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially-deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strength in a heavy deformed nucleus Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in Sm. Conclusions: The new FAM implementation enables calculations of the QRPA strength function throughout the nuclear landscape. This will facilitate global surveys of multipole modes and beta decays, and will open new avenues for constraining the nuclear energy density functional.

    Comments:
    6 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02353 [pdf]
    PRC(2015)·51 citations
  7. 07

    [Submitted on 8 Sept 2015]

    A model of charmed baryon-nucleon potential and 2- and 3-body bound states with charmed baryon

    Saori Maeda (1)🇯🇵 · Makoto Oka (1,2)🇯🇵 · Akira Yokota (1)🇯🇵 · Emiko Hiyama (3)🇯🇵 · Yan-Rui Liu (4) ((1) Tokyo Institute of Technology, (2) Advanced Science Research Center, Japan Atomic Energy Agency, (3) Nishina Center for Accelerator-Based Science, The institute of Physical and Chemical Research (RIKEN), (4) Shandong University)🇨🇳

    A potential model for the interaction between a charmed baryon (, , and ) and the nucleon () is constructed. The model contains a long-range meson ( and ) exchange part and a short-distance quark exchange part. The quark cluster model is used to evaluate the short-range repulsion and a monopole type form factor is introduced to the long-range potential to reflect the extended structure of hadrons. We determine the cutoff parameters in the form factors by fitting the scattering data with the same approach and we obtain four sets of parameters (a -- d). The most attractive potential (d) leads to bound states with and once the channel couplings among , and are taken into account. One can also investigate many-body problems with the model. Here, we construct an effective one-channel potential with the parameter set (d) and apply it to the 3-body system. The bound states with and are predicted.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1509.02445 [pdf]
    PTEP(2016)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE