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Nuclear Theory·nucl-th

Tuesday·September 23, 2025

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 20 Sept 2025]

    Equation of state for hyperonic neutron-star matter in SU(3) flavor symmetry

    Tsuyoshi Miyatsu🇰🇷 · Myung-Ki Cheoun🇰🇷 · Kyungsik Kim🇰🇷 · Koichi Saito🇯🇵

    Using a relativistic mean-field model calibrated to finite-nucleus observables and bulk properties of dense nuclear matter, we investigate hyperonic neutron-star matter within an SU(3) flavor-symmetry scheme. To retain SU(6)-based couplings within SU(3) flavor symmetry, we add a quartic self-interaction and - mixing. We demonstrate the roles of ( ratio), (mixing angle), and (singlet-to-octet coupling ratio) in SU(3)-invariant vector-meson couplings. It is found that predominantly controls the maximum mass of a neutron star, and neutron stars can be supported for . The also helps sustain large masses, whereas has a smaller effect on neutron-star properties. This SU(3) framework reconciles nuclear and astrophysical constraints, and offers a plausible resolution to the hyperon puzzle.

    Comments:
    15 pages, 7 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    2509.16559 [pdf]
    Symmetry(2025)·7 citations
  2. 02

    [Submitted on 20 Sept 2025]

    Solution to the uncertainty problem of nuclear matrix element for neutrinoless double- decay

    J. Terasaki🇨🇿 · O. Civitarese🇦🇷

    The neutrinoless double- decay () of nuclei is one of the major research subjects of neutrino physics nowadays because of its influence on particle physics and astrophysics. The predicted nuclear matrix elements (NMEs) for the decay exhibit large uncertainties depending on the models employed. This problem has affected the development of neutrino physics for many years. We have recently performed the calculation of the NMEs for the and two-neutrino double- decay () modes with a perturbed transition operator and found that the effective axial-vector current coupling is similar for the two decay modes. Based on this finding, we calculate the NMEs using the phenomenological that reproduces the measured half-life of the decay. We apply this method to the NMEs for Xe, Te, and Ge obtained by several groups and show that the uncertainty of the NME is dramatically reduced. Based on this result, we calculate the effective neutrino mass, consistent with the current experimental lower limit of the half-life for the decay. The results indicate that the extracted value of the effective neutrino mass does not yet reach the inverted-mass-hierarchy region allowed by neutrino oscillation data when the lightest neutrino mass is assumed to be below 10 meV. We also calculate the perturbed and NMEs of Pd.

    Comments:
    19 pages, 14 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2509.16605 [pdf]
    0 citations
  3. 03

    [Submitted on 20 Sept 2025]

    Subtracted second Tamm-Dancoff approximation in the relativistic point-coupling model

    Deni Vale · Nils Paar

    Theoretical description of collective nuclear excitations and astrophysically relevant processes require methods going beyond the Random Phase Approximation (RPA) or Tamm-Dancoff Approximation (TDA), which are limited to one-particle-one-hole (1p-1h) configurations. In this work, we introduce the Second Tamm-Dancoff Approximation (STDA) based on the relativistic nuclear energy density functional, which also incorporates two-particle-two-hole (2p-2h) configurations, providing a more comprehensive description of nuclear excitations. Within the relativistic STDA (RSTDA), we implement the subtraction method, that is essential to avoid double counting of correlations and provide realistic description of excited states. Using the DD-PC1 parametrization of the relativistic point-coupling interaction, in the first application of the RSTDA we investigate the properties of isoscalar monopole and quadrupole transitions in 16O. The analysis reveals important role of complex configurations on centroid energies, transition strength distributions, and the fine structure of nuclear response. By resolving the fragmentation and spreading of excitation strength, the RSTDA enables accurate description of experimental spectra.

    Comments:
    38 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2509.16791 [pdf]
    PRC(2025)·2 citations
  4. 04

    [Submitted on 21 Sept 2025]

    Hypernuclear structure with the new leading order covariant chiral hyperon-nucleon force

    Xuan Zeng🇨🇳 · Ru-You Zheng🇨🇳 · Zhi-Wei Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Xian-Rong Zhou🇨🇳

    We have studied single- finite hypernuclear systems spanning from light to heavy masses, employing a new microscopic Lambda-N interaction derived from in-medium interactions within relativistic Brueckner-Hartree-Fock calculations using the leading-order covariant chiral hyperon-nucleon force. Without any adjustable parameters, we have successfully reproduced the experimental results for the single-Lambda binding energies. Although some discrepancies persist in light hypernuclei, the overall calculated binding energies show excellent agreement with the experimental data, and outperforming other microscopic interactions. This study further demonstrates the validity of the leading-order covariant chiral hyperon-nucleon potential and provides a practical set of microscopic interactions for the Skyrme-Hartree-Fock framework.

    Comments:
    9 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2509.16878 [pdf]
    PRC(2026)·1 citation
  5. 05

    [Submitted on 22 Sept 2025]

    A practical approach to perturbative corrections to few-body observables

    Sourav Mondal · Martin Schäfer · Mirko Bagnarol · Nir Barnea · Udit Raha · Johannes Kirscher

    We formulate two methods to facilitate the calculation of perturbative corrections to quantum few-body observables. Both techniques are designed for a numerical realization in combination with any tool that obtains either the entire spectrum or solely the eigenvalues of an operator corresponding to the observable of interest. We exemplify these methods in the context of the nuclear contact theory without pions (Pionless EFT) and benchmark them in the deuteron channel with available analytical, field-theoretical calculations, as well as in the triton and 3-helium channels through earlier extractions within the dibaryon formalism, where in all three systems the point-proton root-mean-square charge radius (rms) was the perturbed observable of choice. Beyond these consistency and accuracy checks, we employ the numerical methods to predict the rms of the 4-helium nuclear ground state to assess three different ways of integrating the Coulomb interaction into Pionless EFT. By comparing the respective results at leading and next-to-leading order for 3- and 4-helium, we find that the uncertainty due to the strong, short-range interaction is significantly larger compared with that due to the long-range Coulomb interaction for both bound states with their different binding momenta. Thereby, we provide strong support for simplifying extractions of bound-state observables by shutting off any Coulomb interaction if the strong part of the potential is considered only up to first order in the effective range expansion.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2509.17366 [pdf]
    4 citations
  6. 06

    [Submitted on 22 Sept 2025]

    Isotropization in heavy ion collisions in the 2PI formalism

    Francois Gelis🇫🇷

    An important question in heavy-ion collisions is how the initial far-from-equilibrium medium evolves and thermalizes while it undergoes a rapid longitudinal expansion. In this presentation, we show how to use the two-particle irreducible (2PI) effective action to address this question, focusing on scalar theory truncated at three loops. We present numerical results for quantities such as the occupation number, the thermal mass, and the number density.

    Comments:
    Talk given at XQCD 2025, Wroclaw
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2509.17668 [pdf]
    J.Subatomic Part.Cosmol.(2025)·0 citations
  7. 07

    [Submitted on 22 Sept 2025]

    Dineutron clusters in He and He structure

    E. Garrido · A.S. Jensen

    The hyper-radial barrier strongly hinders formation of more than three clusters. We investigate how well the dominating cluster components in He and He, respectively can be described as ++ and ++, where is the dineutron. Effective interactions compatible with He and He are used. We vary the lesser known - and - interactions, where very small strengths are required. We provide energies, radii, and partial wave decomposition of all computed, predicted or measured, ground and resonance states. We predict substructures within each of the three-body quantum states. We also calculate the neutron-structure sensitive invariant mass spectrum of the four-nucleon system, after fast removal of the -particle from He. We show that all available experimental information are fairly well reproduced. Very little room is left for variation of the effective interaction parameters. Thus, the dominating features of the subsequently derived reaction and structure properties are well supported.

    Comments:
    To be published in Journal of Physics G: Nuclear and Particle Physics
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2509.17908 [pdf]
    J.Phys.G(2025)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE