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Nuclear Theory·nucl-th

Monday·September 6, 2021

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    [Submitted on 3 Sept 2021]

    Dynamics of light hypernuclei in collisions of Au+Au at GeV energies

    Zhao-Qing Feng🇨🇳

    The dynamics of light hypernuclei and nuclear clusters produced in Au+Au collisions has been investigated thoroughly with a microscopic transport model. All possible channels of hyperon production and transportation of hyperons in nuclear medium are implemented into the model. The light complex fragments are recognized with the Wigner density approach at the stage of freeze out in nuclear collisions. The isospin diffusion in the collisions is responsible for the neutron-rich cluster formation. The collective flows of nuclear clusters are consistent with the experimental data from FOPI collaboration. It is found that the influence of the hyperon-nucleon potential on the free hyperons is negligible, but available for the light hypernuclide formation. The directed and elliptic flows of H and H at incident energies of 2, 2.5, 3, 3.5 and 4 GeV/nucleon are investigated thoroughly and manifest the same structure with the nuclear clusters. The hypernuclear yields are produced in a wide rapidity and momentum regime with increasing the beam energy.

    Comments:
    15 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2002.07359
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2109.01270 [pdf]
    EPJA(2021)·5 citations
  2. 02

    [Submitted on 3 Sept 2021]

    Bayesian evaluation of residual production cross sections in proton induced spallation reactions

    Peng Dan · Hui-Ling Wei · Xi-Xi Chen · Xiao-Bao Wei · Yu-Ting Wang · Jie Pu · Kai-Xuan Cheng · Chun-Wang Ma

    The Bayesian neural network (BNN) method is used to construct a predictive model for fragment prediction of proton induced spallation reactions with the guidance of a simplified EPAX formula. Compared to the experimental data, it is found that the BNN + sEPAX model can reasonably extrapolate with less information compared with BNN method. The BNN + sEPAX method provides a new approach to predict the energy-dependent residual cross sections produced in proton-induced spallation reactions from tens of MeV/u up to several GeV/u.

    Comments:
    9 pages, 1 table, and 7 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2109.01388 [pdf]
    J.Phys.G(2022)·19 citations
  3. 03

    [Submitted on 3 Sept 2021]

    Diffusion matrix associated with the diffusion processes of multiple conserved charges in a hot and dense hadronic matter

    Arpan Das🇵🇱 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳

    Bulk matter produced in heavy ion collisions has multiple conserved quantum numbers like baryon number, strangeness and electric charge. The diffusion process of these charges can be described by a diffusion matrix describing the interdependence of diffusion of different charges. The diffusion coefficient matrix is estimated here from the Boltzmann kinetic theory for the hadronic phase within relaxation time approximation. In the derivation for the same, we impose the Landau-Lifshitz conditions of fit. This leads to e.g. the diagonal diffusion coefficients to be manifestly positive definite. The explicit calculations are performed within the ambit of hadron resonance gas model with and without excluded volume corrections. It is seen that the off-diagonal components can be significant to affect the charge diffusion in a fluid with multiple conserved charges. The excluded volume correction effects is seen to be not significant in the estimation of the elements of the diffusion matrix.

    Comments:
    16 pages, 6 figures, Comments are very much welcome
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2109.01543 [pdf]
    PRD(2022)·17 citations
  4. 04

    [Submitted on 3 Sept 2021]

    Evidence of quadrupole and octupole deformations in Zr+Zr and Ru+Ru collisions at ultra-relativistic energies

    Chunjian Zhang🇺🇸 · Jiangyong Jia🇺🇸

    In the hydrodynamic model description of heavy ion collisions, the elliptic flow and triangular flow are sensitive to the quadrupole deformation and octupole deformation of the colliding nuclei. The relations between and have recently been clarified and were found to follow a simple parametric form. The STAR Collaboration have just published precision data from isobaric Ru+Ru and Zr+Zr collisions, where they observe large differences in central collisions and . Using a transport model simulation, we show that these orderings are a natural consequence of and . We reproduce the centrality dependence of the ratio qualitatively and ratio quantitatively, and extract values of and that are consistent with those measured at low energy nuclear structure experiments. STAR data provide the first direct evidence of strong octupole correlations in the ground state of Zr in heavy ion collisions. Our analysis demonstrates that flow measurements in high-energy heavy ion collisions, especially using isobaric systems, are a new precision tool to study nuclear structure physics.

    Comments:
    6 pages and 3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2109.01631 [pdf]
    PRL(2022)·160 citations

Affiliations

first authorsco-authorsvia INSPIRE