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Nuclear Theory·nucl-th

Thursday·July 24, 2025

14 papers—6 primary·8 cross-listed

All14Primary6Cross-lists8
  1. 01

    [Submitted on 22 Jul 2025]

    Angular correlations in neutron-gamma reactions

    Vladimir Gudkov · Hirohiko M. Shimizu

    Angular correlations for low-energy neutron induced reactions are calculated using nuclear reaction formalism for multi level neutron capture with arbitrary multiplicities of transitions. We confirm previous calculations [V. V. Flambaum and O. P. Sushkov, Nucl. Phys.A 435 , 352 (1985)] for dipole transitions obtained with different formalism. The possible applications of n- correlations for studies of symmetry violations and electromagnetic transitions are discussed.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2507.16885 [pdf]
    PRC(2025)·0 citations
  2. 02

    [Submitted on 22 Jul 2025]

    Hypernuclei with Neural Network Quantum States

    Andrea Di Donna🇮🇹 · Lorenzo Contessi🇫🇷 · Alessandro Lovato🇮🇹 · Francesco Pederiva🇮🇹

    Leveraging complementary machine-learning-based approaches, we compute properties of - and -shell hypernuclei - including binding energies, single-particle densities, and radii - starting from the individual interactions among their constituents. These interactions are modeled using an improved leading-order pionless effective field theory expansion, with coefficients determined via a Gaussian Process framework anchored on virtually exact few-body techniques. We solve the many-body Schrödinger equation using a variational Monte Carlo method based on neural network quantum states, extending it for the first time to include particles alongside protons and neutrons. The predicted binding energies show remarkably good agreement with experimental results, given the simplicity of the input Hamiltonian. We also confirm the experimentally observed shrinkage of the proton radius in Li compared to its parent nucleus, Li. This work paves the way for an ab initio description of medium-mass and heavy hypernuclei, as well as for understanding the onset of strange degrees of freedom in the core of neutron stars.

    Comments:
    15 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2507.16994 [pdf]
    PRResearch(2026)·11 citations
  3. 03

    [Submitted on 22 Jul 2025]

    Probing N interaction through bound states of system

    Faisal Etminan🇮🇷

    The possible bound state of the system is explored within the framework of the three-body cluster model. The calculations are done by employing the state-of-the-art N interactions obtained from the analysis of the pure elastic scattering and the coupled-channel in the correlation functions. The potentials are constructed by two methods: the single-folding potential (SFP) method for the given spin-averaged N potentials in coordinate space, and the optical model potential (OMP) approximation within the multiple-scattering framework for the given scattering length of the N interaction. It is found that, when only the single-channel interactions are employed, the system could be bound with a binding energy in the interval [3-26] MeV. However, the coupled-channel interaction, which is most consistent with experimental measurements, does not yield any bound state, even when the spin-averaged potential is employed, and this potential is found to be more attractive than the corresponding coupled-channel counterpart. It is essential to consider the contributions from the dynamics of the vector-baryon coupled channels interaction. This effect is capable of playing a decisive role in the existence of mesic nuclei.

    Comments:
    16 pages, 3 figure, 3 Tables
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
    arXiv:
    2507.17022 [pdf]
    PRC(2025)·4 citations
  4. 04

    [Submitted on 22 Jul 2025]

    Further steps towards next generation of covariant energy density functionals

    B. Osei · A. V. Afanasjev · A. Taninah · A. Dalbah · U. C. Perera · V. A. Dzuba · V. V. Flambaum

    The present study aims at further development of covariant energy density functionals (CEDFs) towards more accurate description of binding energies across the nuclear chart. For the first time, infinite basis corrections to binding energies in the fermionic and bosonic sectors of the covariant density functional theory have been taken into account in the fitting protocol within the covariant density functional theory. In addition, total electron binding energies have been used in the conversion of atomic binding energies into nuclear ones. Their dependence on neutron excess has been investigated for the first time across the nuclear chart within atomic approach. These factors have been disregarded in previous generation of covariant energy density functionals but their neglect leads to substantial global calculation errors for physical quantities of interest. For example, these errors for binding energies are of the order of 0.8 MeV or higher for the three major classes of covariant energy density functionals.

    Comments:
    16 pages, 9 figures, supplemental material is added at the end of manuscript
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2507.17082 [pdf]
    PRC(2025)·6 citations
  5. 05

    [Submitted on 23 Jul 2025]

    Implications of the recent neutron decay measurements on the properties of compact objects -- a dark star with nucleonic shell ?

    M.Veselský🇨🇿 · V. Petousis🇨🇿 · Ch.C. Moustakidis🇬🇷 · M. Vikiaris🇬🇷

    Recent experimental observation suggests that neutron decay is always accompanied by emission of electron while in 1% of cases proton is not emitted. We develop a scenario kinematically compatible with experimental observation, where neutron decay results in production of two dark matter particles of about half the mass of neutron and test properties of neutron stars with admixture of such particles. Constraints on mass and coupling to vector dark boson are obtained. The structure of the compact object is modified to a dark star with a shell of nucleonic matter around the nuclear saturation density.

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2507.17340 [pdf]
    2 citations
  6. 06

    [Submitted on 23 Jul 2025]

    Simultaneous improvements of nuclear mass and charge radius predictions using multi-task Gaussian process approaches

    Weihu Ye · Niu Wan

    A multi-task Gaussian process (GP) machine learning model is introduced to simultaneously predict two important nuclear observables across the nuclear chart, namely nuclear masses and charge radii. Utilizing 12 physical input features, our multi-task GP consistently outperforms single-task learning, achieving overall root-mean-square deviations of 0.136 MeV for masses and 0.007 fm for charge radii. The good performance of the present model is confirmed by three complementary validations, namely various fractions for training and testing data, further extrapolations for newly reported nuclei far from stability, and popular Garvey-Kelson mass relations. The correlations between the two observables are explicitly analyzed within the multi-task learning framework. Furthermore, by employing the SHapley Additive exPlanations (SHAP) method, we interpret the importance of different features for mass and radius predictions across distinct nuclear regions. These results demonstrate the effectiveness of the multi-task GP approach for high-accuracy nuclear property predictions.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2507.17357 [pdf]
    PRC(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE