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Nuclear Theory·nucl-th

Friday·November 17, 2017

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 16 Nov 2017]

    Proxy-SU(3) symmetry in heavy nuclei: Prolate dominance and prolate-oblate shape transition

    S. Sarantopoulou · D. Bonatsos · I.E. Assimakis · N. Minkov · A. Martinou · R.B. Cakirli · R.F. Casten · K. Blaum

    Using a new approximate analytic parameter-free proxy-SU(3) scheme, simple predictions for the global feature of prolate dominance and for the locus of the prolate-oblate shape transition have been made and compared with empirical data. Emphasis is placed on the mechanism leading to the breaking of the particle-hole symmetry, which is instrumental in shaping up these predictions. It turns out that this mechanism is based on the SU(3) symmetry and the Pauli principle alone, without reference to any specific Hamiltonian.

    Comments:
    10 pages, 4 tables, to appear in the proceedings of the Workshop on Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects (SDANCA17, Sofia 2017), ed. N. Minkov
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1711.05888 [pdf]
    Bulg.J.Phys.(2017)·16 citations
  2. 02

    [Submitted on 16 Nov 2017]

    Nucleon electromagnetic form factors with non-local chiral effective Lagrangian

    Fangcheng He🇨🇳 · P. Wang🇨🇳

    The relativistic version of finite-range-regularisation is proposed. The covariant regulator is generated from the nonlocal Lagrangian. This nonlocal interaction is gauge invariant and is applied to study the nucleon electromagnetic form factors at momentum transfer up to 2 GeV. Both octet and decuplet intermediate states are included in the one loop calculation. Using a dipole regulator with around 0.85 GeV, the obtained form factors, electromagnetic radii as well as the ratios of the form factors are all comparable with the experimental data. This successful application of chiral effective Lagrangian to relatively large momentum transfer make it possible to further investigation of hadron quantities at high .

    Comments:
    14 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1711.05896 [pdf]
    PRD(2018)·28 citations
  3. 03

    [Submitted on 16 Nov 2017]

    Comparison of heavy-ion transport simulations: Collision integral in a box

    Ying-Xun Zhang🇨🇳 · Yong-Jia Wang🇨🇳 · Maria Colonna🇮🇹 · Pawel Danielewicz🇺🇸 · Akira Ono🇯🇵 · Betty Tsang🇺🇸 · Hermann Wolter🇩🇪 · Jun Xu🇨🇳 · Lie-Wen Chen🇨🇳 · Dan Cozma🇷🇴 · Zhao-Qing Feng🇨🇳 · Subal Das Gupta🇨🇦 and 18 other authors

    Simulations by transport codes are indispensable to extract valuable physics information from heavy ion collisions. In order to understand the origins of discrepancies between different widely used transport codes, we compare 15 such codes under controlled conditions of a system confined to a box with periodic boundary, initialized with Fermi-Dirac distributions at saturation density and temperatures of either 0 or 5 MeV. In such calculations, one is able to check separately the different ingredients of a transport code. In this second publication of the code evaluation project, we only consider the two-body collision term, i.e. we perform cascade calculations. When the Pauli blocking is artificially suppressed, the collision rates are found to be consistent for most codes (to within or better) with analytical results, or completely controlled results of a basic cascade code after eliminating the correlations within the same pair of colliding particles. In calculations with active Pauli blocking, the blocking probability was found to deviate from the expected reference values. The reason is found in substantial phase-space fluctuations and smearing tied to numerical algorithms and model assumptions in the representation of phase space. This results in the reduction of the blocking probability in most transport codes, so that the simulated system gradually evolves away from the Fermi-Dirac towards a Boltzmann distribution. As a result of this investigation, we are able to make judgements about the most effective strategies in transport simulations for determining the collision probabilities and the Pauli blocking. Investigation in a similar vein of other ingredients in transport calculations, like the mean field propagation or the production of nucleon resonances and mesons, will be discussed in the future publications.

    Comments:
    23 pages, 10 figures. The abstract is changed a little bit due to the limits character number. The complete abstract is in the paper. Accepted by Phys.Rev.C
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1711.05950 [pdf]
    PRC(2018)·167 citations
  4. 04

    [Submitted on 16 Nov 2017]

    A quark coalescence model for polarized vector mesons and baryons

    Yang-guang Yang🇨🇳 · Ren-hong Fang🇨🇳 · Qun Wang🇨🇳 · Xin-nian Wang🇨🇳

    A non-relativistic quark coalescence model is formulated for polarized vector mesons and baryons of spin-1/2 octet and spin-3/2 decuplet. With the spin density matrix, one can compute in a uniform way the polarizations of vector mesons and baryons from those of quarks and antiquarks with explicit momentum dependence. The results are compared to that obtained from kinetic and statistical models for hadrons.

    Comments:
    Revtex 4, 17 pages, no figure; Appendix B and C have been removed, a new Appendix C is added; The discussions about the comparison between the coalescence model and the hadron statistical model have been expanded. To appear in PRC
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    1711.06008 [pdf]
    PRC(2018)·109 citations

Affiliations

first authorsco-authorsvia INSPIRE