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Nuclear Theory·nucl-th

Tuesday·September 27, 2022

13 papers—6 primary·7 cross-listed

All13Primary6Cross-lists7
  1. 01

    [Submitted on 24 Sept 2022]

    Anisotropic flows of charmonium in the relativistic heavy-ion collisions

    Chenyu Li🇺🇸 · Baoyi Chen🇨🇳

    We review recent studies about anisotropic flows () of charmonium in the quark-gluon plasma produced in relativistic heavy-ion collisions. Collective flows of the bulk medium are developed due to the anisotropic pressure gradient of the medium. Strongly coupled with the bulk medium, charm quarks carry collective flows from the expanding medium, which will be inherited by the regenerated charmonium via the coalescence process. In event-by-event collisions where nucleon positions fluctuate from the smooth distribution, there is triangularity in the medium initial energy density. Triangular flows of the bulk medium and heavy flavor particles can be developed due to the initial fluctuations. In the longitudinal direction, the rapidity-odd distribution of the initial energy density is induced by the rotation of the medium in non-central heavy-ion collisions. Charmonium suffers biased dissociation along positive and negative -directions in forward (backward) rapidity. The directed flow of charmonium becomes non-zero. The directed, elliptic and triangular flows () of charmonium come from the anisotropic initial distributions of the medium energy density in the transverse and longitudinal directions.

    Comments:
    12pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.11996 [pdf]
    Mathematics(2022)·1 citation
  2. 02

    [Submitted on 24 Sept 2022]

    Threshold photoproduction of neutral pions off protons in nuclear model with explicit mesons

    D. V. Fedorov🇩🇰 · M. Mikkelsen🇨🇭

    We apply the nuclear model with explicit mesons to photoproduction of neutral pions off protons at the threshold. In this model the nucleons do not interact with each other via a potential but rather emit and absorb mesons that are treated explicitly on equal footing with the nucleons. We calculate the total cross section of the reaction for energies close to threshold and compare the calculations with available experimental data. We show that the model is able to reproduce the experimental data and determine the range of the parameters where the model is compatible with the experiment.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2209.12071 [pdf]
    Few Body Syst.(2023)·3 citations
  3. 03

    [Submitted on 25 Sept 2022]

    Model study on modification in small collision systems

    Junlee Kim🇰🇷 · Jinjoo Seo🇰🇷 · Byungsik Hong🇰🇷 · Juhee Hong🇰🇷 · Eun-Joo Kim🇰🇷 · Yongsun Kim🇰🇷 · MinJung Kweon🇰🇷 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷 · Jaebeom Park🇰🇷

    Quarkonium production has been studied extensively in relativistic heavy-ion collision experiments to understand the properties of the quark gluon plasma. The experimental results on the yield modification in heavy-ion collisions relative to that in + collisions can be described by several models considering dissociation and regeneration effects. A yield modification beyond initial-state effects has also been observed in small collision systems such as +Au and +Pb collisions, but it is still premature to claim any hot medium effect. A model study in various small collision systems such as +, +Pb, +O, and O+O collisions will help quantitatively understanding nuclear effects on the production. A theoretical calculation considering the gluo-dissociation and inelastic parton scattering and their inverse reaction reasonably describes the suppression of in Pb+Pb collisions. Based on this calculation, a Monte-Carlo simulation is developed to more realistically incorporate the medium produced in heavy-ion collisions with event-by-event initial collision geometry and hydrodynamic evolution. We extend this framework to small systems to study the medium effects. In this work, we quantify the nuclear modification factor of as a function of charged particle multiplicity () and transverse momentum. We also calculate the elliptic flow of in small collision systems.

    Comments:
    11 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2209.12303 [pdf]
    PRC(2023)·11 citations
  4. 04

    [Submitted on 26 Sept 2022]

    Spin Boltzmann equation for non-relativistic spin-1/2 fermions

    Wen-Bo Dong🇨🇳 · Yi-Liang Yin🇨🇳 · Qun Wang🇨🇳

    We derive the spin Boltzmann equations for spin-1/2 fermions in a non-relativistic model with four-fermion contact interaction which conserves spin degrees of freedom. A great advantage of the model is that the spin matrix elements in collision terms can be completely worked out and be put into such a compact form that one can clearly see how spins are coupled in particle scatterings. A semi-classical expansion in the Planck constant has been made and the on-shell part of the spin Boltzmann equation up to the next-to-leading order is derived. At the leading order the equilibrium spin distribution can be obtained from the vanishing of the collision term for the spin density. The spin chemical potential emerges as a natural consequence of spin conservation. The off-shell part of the spin Boltzmann equation is also discussed. The work can be extended to more sophisticated interaction such as nuclear force in order to apply to spin polarization phenomena in heavy-ion collisions at low energies.

    Comments:
    RevTex 4, 15 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.12402 [pdf]
    PRC(2022)·4 citations
  5. 05

    [Submitted on 26 Sept 2022]

    Systematic study of proton radioactivity half-lives based on the relationship between the Skyrme-Hartree-Fock and the macroscopic quantities of nuclear matter

    Jun-Hao Cheng · Zhen Zhang · Xi-Jun Wu · Peng-Cheng Chu · Xiao-Hua Li

    In the present work, we systematically study the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between the Skyrme parameters and the macroscopic quantities of nuclear matter. Using the two-potential approach with the spherical Skyrme-Hartree-Fock model, the correlation between proton radioactivity half-life and macroscopic quantities was analyzed. Moreover, we obtained a new Skyrme parameter set by fitting the two most weighted macroscopic quantities. Compared with Skyrme parameters MSL0 and the theoretical model of proton radioactivity UDLP, the theoretical proton radioactivity half-life calculated by the new Skyrme parameter set can better reproduce the experimental data.

    Comments:
    8 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.12615 [pdf]
    CPC(2022)·2 citations
  6. 06

    [Submitted on 26 Sept 2022]

    Role of vector self-interaction in Neutron Star properties

    Bikram Keshari Pradhan · Debarati Chatterjee · Radhika Gandhi · Jürgen Schaffner-Bielich

    Previous studies have claimed that there exist correlations among certain nuclear saturation parameters and neutron star observables, such as the slope of the symmetry energy and the radius of a neutron star. However, it is not clear whether such correlations are physical or spurious, as they are not observed universally for all equation of state models. In this work, we probe the role of vector self-interaction within the framework of the Relativistic Mean Field model and its role in governing the observable stellar properties and their correlations with nuclear parameters. We confirm that the effect of this term is not only to control the high density properties of the equation of state but also to govern such correlations. We also impose a limit on the maximum strength of the vector self-interaction using recent astrophysical data.

    Comments:
    14 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2209.12657 [pdf]
    NPA(2023)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE