PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·September 5, 2017

13 papers—5 primary·8 cross-listed

All13Primary5Cross-lists8
  1. 01

    [Submitted on 3 Sept 2017]

    High-momentum antisymmetrized molecular dynamics compared with tensor-optimized shell model for strong tensor correlation

    Takayuki Myo · Hiroshi Toki · Kiyomi Ikeda · Hisashi Horiuchi · Tadahiro Suhara · Mengjiao Lyu · Masahiro Isaka · Taiichi Yamada

    We treat the tensor correlation in antisymmetrized molecular dynamics (AMD) including large-relative-momentum components among nucleon pairs for finite nuclei. The tensor correlation is described by using large imaginary centroid vectors of Gaussian wave packets for nucleon pairs with opposite directions, which makes a large relative momentum. We superpose the AMD basis states, in which one nucleon pair has various relative momenta for all directions; this new method is called "high-momentum AMD" (HM-AMD). We show the results for He using the effective interaction having a strong tensor force. It is found that HM-AMD provides a large tensor matrix element comparable to the case of the tensor-optimized shell model (TOSM), in which the two-particle-two-hole (2p-2h) excitations are fully included to describe the tensor correlation. The results of two methods agree with each other at the level of the Hamiltonian components of He. This indicates that in HM-AMD the high-momentum components described by the imaginary centroid vectors of the nucleon pair provide the equivalent effect of the 2p-2h excitations for the tensor correlation.

    Comments:
    11 pages, 4 figures, added references
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1709.00660 [pdf]
    PTEP(2017)·25 citations
  2. 02

    [Submitted on 4 Sept 2017]

    Global analysis of Skyrme forces with higher-order density dependence

    Z.W. Zuo · J.C. Pei · X.Y. Xiong · Y. Zhu

    The density dependent term in Skyrme forces is essential, which simulates three-body and many-body correlations beyond the low-momentum two-body interaction. We speculate that a single density term may be insufficient and a higher-order density dependent term is added. The present work investigates the influences of higher-order density dependencies based on extended UNEDF0 and SkM* forces. The global descriptions of nuclear masses and charge radii have been presented. Consequently the extended UNEDF0 force gives a global rms error on binding energies of 1.29 MeV. The influences on fission barriers and equation of state have also been investigated. The perspectives to improve Skyrme forces have also been discussed, including global center-of-mass corrections and Lipkin-Nogami pairing corrections.

    Comments:
    8 pages, 9 figures, to be published in Chin.Phys.C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1709.00802 [pdf]
    CPC(2018)·11 citations
  3. 03

    [Submitted on 4 Sept 2017]

    Higher order net-proton number cumulants dependence on the centrality definition and other spurious effects

    S. Sombun🇹🇭 · J. Steinheimer🇩🇪 · C. Herold🇹🇭 · A. Limphirat🇹🇭 · Y. Yan🇹🇭 · M. Bleicher🇩🇪

    We study the dependence of the normalized moments of the net-proton multiplicity distributions on the definition of centrality in relativistic nuclear collisions at a beam energy of GeV. Using the UrQMD model as event generator we find that the centrality definition has a large effect on the extracted cumulant ratios. Furthermore we find that the finite efficiency for the determination of the centrality introduces an additional systematic uncertainty. Finally, we quantitatively investigate the effects of event-pile up and other possible spurious effects which may change the measured proton number. We find that pile-up alone is not sufficient to describe the data and show that a random double counting of events, adding significantly to the measured proton number, affects mainly the higher order cumulants in most central collisions.

    Comments:
    10 pages 13 figures, version accepted by JPG
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1709.00879 [pdf]
    J.Phys.G(2018)·19 citations
  4. 04

    [Submitted on 4 Sept 2017]

    Many-body forces in magnetic neutron stars

    R.O. Gomes · B. Franzon · V. Dexheimer · S. Schramm

    In this work, we study in detail the effects of many-body forces on the equation of state and the structure of magnetic neutron stars. The stellar matter is described within a relativistic mean field formalism that takes into account many-body forces by means of a non-linear meson field dependence on the nuclear interaction coupling constants. We assume that matter is at zero temperature, charge neutral, in beta-equilibrium, and populated by the baryon octet, electrons, and muons. In order to study the effects of different degrees of stiffness in the equation of state, we explore the parameter space of the model, which reproduces nuclear matter properties at saturation, as well as massive neutron stars. Magnetic field effects are introduced both in the equation of state and in the macroscopic structure of stars by the self-consistent solution of the Einstein-Maxwell equations. In addition, effects of poloidal magnetic fields on the global properties of stars, as well as density and magnetic field profiles are investigated. We find that not only different macroscopic magnetic field distributions, but also different parameterizations of the model for a fixed magnetic field distribution impact the gravitational mass, deformation and internal density profiles of stars. Finally, we also show that strong magnetic fields affect significantly the particle populations of stars

    Comments:
    accepted by The Astrophysical Journal
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1709.01017 [pdf]
    ApJ(2017)·33 citations
  5. 05

    [Submitted on 4 Sept 2017]

    Collective excitations of a hot anisotropic QCD medium with Bhatnagar-Gross-Krook collisional kernel within an effective description

    Avdhesh Kumar🇮🇳 · M. Yousuf Jamal🇮🇳 · Vinod Chandra🇮🇳 · Jitesh R. Bhatt🇮🇳

    Collective modes of an anisotropic hot QCD medium have been studied within the semi-classical transport theory employing Bhatnagar-Gross-Krook (BGK) collisional kernel. The modeling of the isotropic medium is primarily based on a recent quasi-particle description of hot QCD equation of state where the medium effects have been encoded in effective gluon and quark/anti-quark momentum distributions that posses non-trivial energy dispersions. The anisotropic distribution functions are obtained in a straightforward the way by stretching or squeezing the isotropic ones along one of the directions. The gluon self-energy is computed using these distribution functions in a linearized transport equation with Bhatnagar-Gross-Krook (BGK) collisional kernel. Further, the tensor decomposition of gluon self-energy leads to the structure functions which eventually controls the dispersion relations and the collective mode structure of the medium. It has been seen that both the medium effects and collisions induce appreciable modifications to the collective modes and plasma excitations in the hot QCD medium.

    Comments:
    16 pages, 20 figures, two column
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1709.01032 [pdf]
    PRD(2018)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE