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Nuclear Theory·nucl-th

Friday·January 20, 2023

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 18 Jan 2023]

    Flow Distribution Analysis as A Probe of Nuclei Deformity

    Hadi Mehrabpour🇩🇪 · S. M. A. Tabatabaee🇮🇷

    We study the flow harmonic distribution in deformed nuclei. To do this, we use the standard Gram-Charlier method to find the higher-order correction to the well-known Bessel-Gaussian distribution. We find that, apart from the necessity of including a shift parameter , the modified flow distribution describes the flow distribution of quadrupole and octupole deformation accurately. Using the shifted radial distribution, arising from this method, we scrutinize the effect of deformation on flow distribution. Assuming a linear relation between observables of spherical and deformed collisions, , for events with a fixed centrality, we compare the flow distribution of deformed and spherical nuclei. We also propose a way to measure in asymmetric nuclei collisions.

    Comments:
    11 pages and 11 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.07770 [pdf]
    PRC(2023)·7 citations
  2. 02

    [Submitted on 19 Jan 2023]

    Bayesian inference of nucleus resonance and neutron skin

    Jun Xu🇨🇳

    In this proceeding, we have presented some highlight results on the constraints of the nuclear matter equation of state (EOS) from the data of nucleus resonance and neutron-skin thickness using the Bayesian approach based on the Skyrme-Hartree-Fock model and its extension. Typically, we have discussed the anti-correlation and positive correlation between the slope parameter and the value of the symmetry energy at the saturation density under the constraint of, respectively, the neutron-skin thickness and the isovector giant dipole resonance. We have shown that the Bayesian analysis can help to find a compromise for the ``PREXII puzzle'' and the ``soft Tin puzzle". We have further illustrated the possible modifications on the constraints of lower-order EOS parameters as well as the relevant correlation when higher-order EOS parameters are incorporated as independent variables. For a given model and parameter space, the Bayesian approach serves as a good analysis tool suitable for multi-messengers versus multi-variables, and is helpful for constraining quantitatively the model parameters as well as their correlations.

    Comments:
    10 pages, 8 figures, proceeding of the workshop on applications of machine learning in nuclear physics and nuclear data, Rui Chang, Jiangxi province, China, Aug. 5-7 th, 2022
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.07884 [pdf]
    Atomic Energ.Sci.Technol.(2023)·1 citation
  3. 03

    [Submitted on 19 Jan 2023]

    Measuring deformed neutron skin with free spectator nucleons in relativistic heavy-ion collisions

    Lu-Meng Liu🇨🇳 · Jun Xu🇨🇳 · Guang-Xiong Peng🇨🇳

    The neutron skin in deformed nuclei is generally not uniformly distributed but has an angular distribution, depending on both the spin-dependent nuclear interaction and the nuclear symmetry energy. To extract the information of the deformed neutron skin, we have explored the possibility of using free spectator nucleons in central tip-tip and body-body collisions at top RHIC energy with four typical deformed nuclei. The density distributions of neutrons and protons are consistently obtained from the Skyrme-Hartree-Fock-Bogolyubov calculation, and the angular distribution of the neutron skin can be varied by adjusting the strength of the nuclear spin-orbit coupling. With the information of spectator nucleons obtained based on a Monte-Carlo Glauber model, the free spectator nucleons are generated from a multifragmentation process. By investigating the results from different systems and with different collision configurations, we found that although it is difficult to probe the deformed neutron skin in Zr and U by their collisions, it is promising to extract the polar angular distributions of the neutron skin in Ru and Au by comparing the yield ratios of free spectator neutrons to protons in their central tip-tip and body-body collisions. The proposed observables can be measured by dedicated zero-degree calorimeters in heavy-ion collision experiments that have been carried out in recent years by RHIC.

    Comments:
    7 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.07893 [pdf]
    PLB(2023)·23 citations
  4. 04

    [Submitted on 19 Jan 2023]

    Bayesian inference of neutron-star observables based on effective nuclear interactions

    Jia Zhou🇨🇳 · Jun Xu🇨🇳 · Panagiota Papakonstantinou🇰🇷

    Based on the Skyrme-Hartree-Fock model (SHF) as well as its extension (the Korea-IBS-Daegu-SKKU (KIDS) model) and the relativistic mean-field (RMF) model, we have studied the constraints on the parameters of the nuclear matter equation of state (EOS) from adopted astrophysical observables using a Bayesian approach. While the masses and radii of neutron stars generally favors a stiff isoscalar EOS and a moderately soft nuclear symmetry energy, model dependence on the constraints is observed and mostly originates from the incorporation of higher-order EOS parameters and difference between relativistic and non-relativistic models. At twice saturation density, the value of the symmetry energy is constrained to be MeV in the standard SHF model, MeV in the KIDS model, and MeV in the RMF model, around their maximum {\it a posteriori} values within confidence intervals. Our study helps to obtain a robust constraint on nuclear matter EOS, and meanwhile, to understand the model dependence of the results.

    Comments:
    16 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2301.07904 [pdf]
    PRC(2023)·25 citations
  5. 05

    [Submitted on 19 Jan 2023]

    Revisiting angular momentum conservation in transport simulations of intermediate-energy heavy-ion collisions

    Rong-Jun Liu🇨🇳 · Jun Xu🇨🇳

    Based on the well-calibrated IBUU transport model, we have studied the dynamical effect of incorporating rigorous angular momentum conservation in each collision of particles with homework setups. The constraint of the rigorous angular momentum conservation requires in-plane collisions and side jumps of particles after their collision. Since the option is not unique, we have compared two typical prescriptions with the original one. While the results depend quantitatively on the choice of the prescription, we found that the angular momentum conservation generally reduces local density fluctuations and thus the collision rate, and may have some influence on the density evolution, the collective flow, and even the pion production in transport simulations of intermediate-energy heavy-ion collisions.

    Comments:
    8 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.07907 [pdf]
    Universe(2023)·3 citations
  6. 06

    [Submitted on 19 Jan 2023]

    Shear viscosity of nuclear matter in the spinodal region

    Lei-Ming Hua🇨🇳 · Jun Xu🇨🇳

    Based on IBUU simulations calibrated by previous efforts of the transport model evaluation project, we have studied the specific shear viscosity of nuclear matter in the spinodal region using the Green-Kubo method. With the momentum-independent mean-field potential which reproduces reasonably well empirical nuclear matter properties and nuclear phase diagram, we have generated dynamically stable and thermalized nuclear cluster systems in a box with the periodic boundary condition. Extensive results of the at different average densities and temperatures in uniform and non-uniform systems are compared, and we found that the shear viscosity is smaller with nuclear clusters due to the enhanced correlation of the energy-momentum tensor and the stronger collision effect. The temperature dependence of the has a minimum only at low average densities of . The present study serves as a rigorous baseline calculation of the in nuclear systems with clusters, and helps to understand the relation between the shear viscosity and the nuclear phase diagram.

    Comments:
    12 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2301.07922 [pdf]
    PRC(2023)·3 citations
  7. 07

    [Submitted on 19 Jan 2023]

    Spanning the full range of neutron star properties within a microscopic description

    Tuhin Malik🇵🇹 · Márcio Ferreira🇵🇹 · Milena Bastos Albino🇵🇹 · Constança Providência🇵🇹

    The high-density behavior of nuclear matter is analyzed within a relativistic mean-field description with non-linear meson interactions. To assess the model parameters and their output, a Bayesian inference technique is used. The Bayesian setup is limited only by a few nuclear saturation properties, the neutron star maximum mass larger than 2 M, and the low-density pure neutron matter equation of state (EOS) produced by an accurate NLO calculation in chiral effective field theory. Depending on the strength of the non-linear scalar vector field contribution, we have found three distinct classes of EOSs, each one correlated to different star properties distributions. If the non-linear vector field contribution is absent, the gravitational maximum mass and the sound velocity at high densities are the greatest. However, it also gives the smallest speed of sound at densities below three times saturation density. On the other hand, models with the strongest non-linear vector field contribution predict the largest radii and tidal deformabilities for 1.4 M stars, together with the smallest mass for the onset of the nucleonic direct Urca processes and the smallest central baryonic densities for the maximum mass configuration. These models have the largest speed of sound below three times saturation density, but the smallest at high densities, in particular, above four times saturation density the speed of sound decreases approaching approximately at the center of the maximum mass star. On the contrary, a weak non-linear vector contribution gives a monotonically increasing speed of sound. A 2.75 M NS maximum mass was obtained in the tail of the posterior with a weak non-linear vector field interaction. We found that pQCD favors models with a large non-linear vector field contribution or hyperons.

    Comments:
    There are 17 pages, 16 figures (The typographical error in the supplemental update)
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2301.08169 [pdf]
    PRD(2023)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE