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Nuclear Theory·nucl-th

Wednesday·April 6, 2016

9 papers—7 primary·2 cross-listed

All9Primary7Cross-lists2
  1. 01

    [Submitted on 4 Apr 2016]

    Ferro-deformation and shape phase transitions over the nuclear chart: 50 < protons (Z) < 82 and 50 < neutrons (N) < 126

    Chang-Bum Moon

    We study a global nuclear structure in the framework of experimental observables. With the aid of large nuclear structure data at the national nuclear data center, NNDC, we present the distinctive systematic patterns emerged in the first 2+ excited energies, E(2+) and their energy ratios to the first 4+ levels, R = E(4+)/E(2+), in the even-even nuclei, over 50 < Z < 82 for protons, and 50 < N < 126 for neutrons. We introduce the so-called pseudo-shell configurations from the subshells mixture in order to explain a semi-double shell closure, a shape phase transition, and a reinforced deformation. It is found that the reinforced deformation arises when Z = 64 or 66 correlates with N = 90 and reaches its maximum, indicating R = 3.3. Such a saturated reinforced deformation spans over Z = 58 to 72 and N = 100 to 106 as showing its center at Z = 64 or 66 and at N = 102 or 104. We define this reinforced deformation 'a ferro-deformation' like a ferro-magnetism in condensed matter physics. The shape coexistence would be expected to occur, such as a ferro-deformation, with a strong rotational mode, and a near spherical shape, with a vibrational mode, at the critical points of Z = 64 or 66, with N = 88 and 90; 150Sm and 152Sm, 152Gd and 154Gd, and 154Dy and 156Dy. We suggest that a super-deformation, which can be formed at high-lying excited states in a moderate deformed nucleus, would correspond to the ferro-deformation at N = 88 for the nuclei; Sm, Gd, and Dy. We argue that the ferro-deformation can be closely associated with a strong spin-orbital interaction between neutrons and protons in the spin-orbit doublet, h9/2-h11/2, leading to the critical points at Z, N = 64, 104.

    Comments:
    11pages, 10 figures,Keywords: national nuclear data center (NNDC), nuclear shell closure, pseudo-(sub)shell, shape phase transition, ferro-deformation, shape coexistence, isospin dependent spin-orbital interaction. Nuclides: Ru, Pd, Cd, Sn, Te, Xe, Ba, Ce, Nd, Sm, Gd, Dy, Er, Yb, Hf, W, Os, Pt, Hg, Pb
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1604.01017 [pdf]
    5 citations
  2. 02

    [Submitted on 4 Apr 2016]

    Calculation of phases of np- scattering up to Tlab=3 GeV for potentials Argonne group on the phase-function method

    V.I. Zhaba🇺🇦

    For calculation of the single-channel nucleon-nucleon scattering a phase-functions method has been proposed. Using a phase-functions method the following phase shifts of a np- scattering numerically for 1S0-, 1P1-, 3P0-, 3P1-, 1D2-, 3D2-, 1F3-, 3F3-, 1G4-, 3G4- states are calculated. The calculations has been performed using realistic nucleon-nucleon potentials Argonne group (Av18, Av14sscc, Av8', Av8'sscc, Av6', Av4', Av2'). Obtained phase shifts are in good agreement with the results obtained in the framework of other methods. Using the obtained phase shifts we have calculated the full cross-section np- scattering.

    Comments:
    in Ukrainian
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1604.01058 [pdf]
    Prob.Atomic Sci.Technol.(2016)·0 citations
  3. 03

    [Submitted on 5 Apr 2016]

    Influence of coalescence parameters on the production of protons and Helium-3 fragments

    Qingfeng Li🇨🇳 · Yongjia Wang🇨🇳 · Xiaobao Wang🇨🇳 · Caiwan Shen🇨🇳

    The time evolution of protons and He fragments from Au+Au/Pb+Pb reactions at 0.25, 2, and 20 GeVnucleon is investigated with the potential version of the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model combined with the traditional coalescence afterburner. In the coalescence process, the relative distance and relative momentum are surveyed in the range of 3-4 fm and 0.25-0.35 GeVc, respectively. For both clusters, a strong reversed correlation between and is seen and it is time-dependent as well. For protons, the accepted (, ) bands lie in the time interval 30-60 fmc, while for He, a longer time evolution (at about 60-90 fmc) is needed. Otherwise, much smaller and values should be chosen. If we further look at the rapidity distributions from both central and semi-central collisions, it is found that the accepted [)] assemble can provide consistent results for proton yield and collective flows especially at mid-rapdities, while for He, the consistency is destroyed at both middle and projectile-target rapidities.

    Comments:
    14 pages, 4 figures.Submitted
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1604.01098 [pdf]
    SCPMA(2016)·14 citations
  4. 04

    [Submitted on 5 Apr 2016]

    Realistic description of the rotational bands in rare earth nuclei by angular-momentum-projected multi-cranked configuration-mixing method

    Mitsuhiro Shimada · Shingo Tagami · Yoshifumi R. Shimizu

    Recently we have proposed a reliable method to describe the rotational band in a fully microscopic manner. The method has recourse to the configuration-mixing of several cranked mean-field wave functions after the angular-momentum-projection. By applying the method with the Gogny D1S force as an effective interaction, we investigate the moments of inertia of the ground state rotational bands in a number of selected nuclei in the rare earth region. As another application we try to describe, for the first time, the two-neutron aligned band in Er, which crosses the ground state band and becomes the yrast states at higher spins. Fairly good overall agreements with the experimental data are achieved; for nuclei, where the pairing correlations are properly described, the agreements are excellent. This confirms that the previously proposed method is really useful for study of the nuclear rotational motion.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1604.01167 [pdf]
    PRC(2016)·11 citations
  5. 05

    [Submitted on 5 Apr 2016]

    Thermal production of charm quarks in heavy ion collisions at Future Circular Collider

    Yunpeng Liu · Che-Ming Ko🇺🇸

    By solving the rate equation in an expanding quark-gluon plasma, we study thermal production of charm quarks in central Pb+Pb collisions at the Future Circular Collider. With the charm quark production cross section taken from the perturbative QCD at the next-to-leading order, we find that charm quark production from the quark-gluon plasma can be appreciable compared to that due to initial hard scattering between colliding nucleons.

    Comments:
    4 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1604.01207 [pdf]
    J.Phys.G(2016)·10 citations
  6. 06

    [Submitted on 5 Apr 2016]

    Power Counting and Wilsonian Renormalization in Nuclear Effective Field Theory

    Manuel Pavon Valderrama🇨🇳

    Effective field theories are the most general tool for the description of low energy phenomena. They are universal and systematic: they can be formulated for any low energy systems we can think of and offer a clear guide on how to calculate predictions with reliable error estimates, a feature that is called power counting. These properties can be easily understood in Wilsonian renormalization, in which effective field theories are the low energy renormalization group evolution of a more fundamental ---perhaps unknown or unsolvable--- high energy theory. In nuclear physics they provide the possibility of a theoretically sound derivation of nuclear forces without having to solve quantum chromodynamics explicitly. However there is the problem of how to organize calculations within nuclear effective field theory: the traditional knowledge about power counting is perturbative but nuclear physics is not. Yet power counting can be derived in Wilsonian renormalization and there is already a fairly good understanding of how to apply these ideas to non-perturbative phenomena and in particular to nuclear physics. Here we review a few of these ideas, explain power counting in two-nucleon scattering and reactions with external probes and hint at how to extend the present analysis beyond the two-body problem.

    Comments:
    Contribution to the IJMPE special issue on "Effective Field Theories in Nuclear Physics". This update includes the corrections and changes of the published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1604.01332 [pdf]
    IJMPE(2016)·49 citations
  7. 07

    [Submitted on 5 Apr 2016]

    Quantum Monte Carlo calculations of two neutrons in finite volume

    P. Klos🇩🇪 · J. E. Lynn🇩🇪 · I. Tews🇺🇸 · S. Gandolfi🇺🇸 · A. Gezerlis🇨🇦 · H.-W. Hammer🇩🇪 · M. Hoferichter🇺🇸 · A. Schwenk🇩🇪

    Ab initio calculations provide direct access to the properties of pure neutron systems that are challenging to study experimentally. In addition to their importance for fundamental physics, their properties are required as input for effective field theories of the strong interaction. In this work, we perform auxiliary-field diffusion Monte Carlo calculations of the ground and first excited state of two neutrons in a finite box, considering a simple contact potential as well as chiral effective field theory interactions. We compare the results against exact diagonalizations and present a detailed analysis of the finite-volume effects, whose understanding is crucial for determining observables from the calculated energies. Using the Lüscher formula, we extract the low-energy S-wave scattering parameters from ground- and excited-state energies for different box sizes.

    Comments:
    11 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1604.01387 [pdf]
    PRC(2016)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE