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Nuclear Theory·nucl-th

Monday·June 1, 2026

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 28 May 2026]

    Time-ordered Diagrammatic Monte Carlo for atomic nuclei

    Stefano Brolli · Carlo Barbieri

    Diagrammatic Monte Carlo provides a systematically improvable framework for stochastically resumming many-body expansions to high orders through direct sampling of diagram topologies. We advance our earlier work by introducing a novel time-ordered Diagrammatic Monte Carlo algorithm for the single-particle Green's function. The algorithm is tailored to finite nuclei, formulated in discrete model spaces and applicable to arbitrary two-body interactions. The new time-ordered diagrammatic Monte Carlo algorithm is based on the on-the-fly evaluation of time-ordered Goldstone diagrams, avoiding explicit diagram enumeration and expensive frequency integration. We show the algorithm by computing O up to fifth order in a reduced model space using optimized reference state orbitals and including effective three-body forces. Benchmarking against established truncation schemes in ab initio nuclear theory demonstrates its potential to overcome the limitations of current many-body approaches.

    Comments:
    6 pages, 5 figures for the main article; 6 pages, 2 figures for supplemental material
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.30527 [pdf]
    1 citation
  2. 02

    [Submitted on 28 May 2026]

    Effects of the Symmetry energy slope on the exotic content of the neutron stars

    Luiz L. Lopes🇧🇷

    By varying the symmetry energy slope (), I investigate how the exotic content within the interiors of neutron stars changes and how it affects both macroscopic and microscopic quantities. Using two different parametrizations (L3 and BigApple), and three different possibilities about the neutron star core (nucleons+hyperons, nucleons+deltas, nucleons+hyperons+deltas), I show that, for the models analyzed in this work, changing the slope barely changes the amount of hyperons, but it can strongly suppress the resonances for large values of . I also show that, in general, the presence of exotic content will be more evident for lower values of than for large ones. Differences and similarities between the two parametrizations are also analyzed.

    Comments:
    16 pages - 6 Figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Theory (hep-th)
    arXiv:
    2605.30554 [pdf]
    1 citation
  3. 03

    [Submitted on 29 May 2026]

    Optimized basis of covariant density functional theory: point coupling functionals and excited states

    A. Dalbah · A. V. Afanasjev · B. Osei

    The present investigation focuses on the improvement of the accuracy of the description of physical observables of interest in moderately sized fermionic basis within the framework of covariant density functional theory. It extends previous study of Ref. [1] to point coupling (PC) covariant energy density functionals (CEDFs) and to excited states. Using as a benchmark the solutions corresponding either to infinite fermionic basis or those extrapolated to such a basis it is shown that the optimization of oscillator frequency of the harmonic oscillator (HO) basis leads to a substantial improvement in the description of different physical observables in the fermionic basis truncated at . Globally optimized scaling factors of the oscillator frequency and the sizes of the HO bases providing the required accuracy in the calculations of the binding energies are generated for the PC functionals. The optimization of the basis also significantly improves the accuracy of the description of potential energy curves, defining the fission barriers and fission isomers in actinides and superheavy nuclei, provided that the size of the basis is at least equal to . The optimization of the HO basis improves the accuracy of the description of the energies of bound single-particle states: the only exceptions are weakly bound neutron states with low orbital momenta , 1 and 2. It is demonstrated for the first time that the halo densities of neutron halo nuclei generated in the coordinate space calculations are well reproduced in the calculations with very large fermionic HO bases.

    Comments:
    16 pages, 15 figures, submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.30669 [pdf]
    1 citation
  4. 04

    [Submitted on 29 May 2026]

    Dynamical selection of fragment shell effects in spontaneous fission of Pu, Th, and Fm

    Qiafeng Chen · Fuchang Gu · Yingge Huang · Erxi Xiao · Yinu Zhang · Jun Su

    Understanding how fragment shell effects influence spontaneous fission mass yields remains a central challenge in nuclear fission theory. This work investigates the role of shell effects in the spontaneous fission of Pu, Th, and Fm by combining microscopic collective dynamics with fragment-level shell analysis. A two-step framework is employed: first, the tunneling from the inner to outer turning points is described using the Wentzel-Kramers-Brillouin approximation along the least-action path on a potential energy surface calculated from constrained Hartree-Fock-Bogoliubov theory. Second, the dissipative descent from the outer turning points to scission is simulated via Langevin dynamics in a large collective space of quadrupole and octupole deformations. Fragment shell effects are quantified using smoothed level density indicators for representative even-even fragment pairs extracted from Langevin scission configurations. The analysis reveals that enhanced yields arise from a coherent overlap among dynamically populated scission configurations, low-energy regions on the fragment potential energy surfaces, and low neutron and/or proton level densities near the Fermi surface. Proton shell effects provide persistent microscopic selectivity in both light and heavy fragments across asymmetric channels, while neutron shell effects offer additional stabilization. Deformed shell effects at finite quadrupole and octupole deformations play a crucial role in stabilizing asymmetric fission channels. This work demonstrates that fission fragment yields reflect shell-favored configurations that are made accessible by the potential energy surface topology and populated by stochastic dynamics, with the largest yields corresponding to configurations where shell gaps provide maximal binding.

    Comments:
    12 pages, 9 figures, comments and suggestions are welcome
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.30828 [pdf]
    PRC(2026)·0 citations
  5. 05

    [Submitted on 29 May 2026]

    Neural-network excited states of nuclei and hypernuclei

    Zi-Xiao Zhang🇮🇳 · Yi-Long Yang🇮🇳 · Xiao-Lu Qian🇮🇳 · Wan-Bing He🇮🇳 · Peng-Wei Zhao🇮🇳 · Bing-Nan Lu🇮🇳 · Yu-Gang Ma🇮🇳

    We present the first variational Monte Carlo study of nuclear and hypernuclear excited states within the neural-network quantum states (NQS) framework. We implement both the overlap penalty (OP) and natural excited state (NES) methods to compute low-lying excitation spectra. To address the spin contamination in hypernuclear calculations, we propose a quantum number targeting (QNT) technique for the OP method. Both the OP-QNT and NES methods can reproduce diagonal observables, such as energies and spatial structures, in excellent agreement with rigorous benchmarks. We further provide, to our knowledge, the first \textit{ab initio} calculation of the transition strength for . The calculated transition strength is consistent with the weak-coupling limit, exhibiting a 1.3\% suppression. This work demonstrates that NQS can be elevated from ground-state solvers to practical tools for nuclear and hypernuclear spectroscopy.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.30944 [pdf]
    2 citations
  6. 06

    [Submitted on 29 May 2026]

    High-Dimensional Bayesian Calibration of Expensive Nuclear Models with Differentiable Emulation

    Jin Lei

    Full Bayesian calibration of expensive nuclear models has been blocked not by the cost of any single solve, but by the absence of exact likelihood gradients in legacy parameter-dependent operators, which forces gradient-free samplers to spend evaluations exploring high-dimensional correlated posteriors. I introduce DREAM, a differentiable calibration strategy in which the parameter-dependent operator is sampled offline by any legacy code, compressed by singular value decomposition, and reconstructed online in a differentiable framework so that automatic differentiation delivers exact likelihood gradients through the full forward solve at the cost of one additional evaluation per Hamiltonian Monte Carlo step. The construction is operator-level and depends only on smooth, compressible parameter dependence; the underlying physics solver is treated as a black box. As a representative demonstration, DREAM is applied to a continuum-discretized coupled-channels (CDCC) analysis of +Ni elastic scattering at ~MeV with eighteen optical-potential parameters, for which No-U-Turn Sampling converges on a single GPU in under ten minutes from a cold start with zero divergent transitions, yielding a full Bayesian posterior for a breakup reaction. The mean emulator error is more than an order of magnitude below the inferred model discrepancy, so the posterior is set by the reaction model rather than the surrogate. Treating the Koning-Delaroche systematics as an informative prior, the data update the well-determined parameter combinations, raising the mean deuteron surface absorption about above the Koning-Delaroche value, while the under-determined directions remain at the prior; this is a representative payoff that the multi-energy datasets DREAM is designed to accommodate can sharpen into a full physics interpretation.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.30980 [pdf]
    0 citations
  7. 07

    [Submitted on 29 May 2026]

    Accessing Exotic Hadronic States via Charmed-Meson Femtoscopy in Relativistic Heavy-Ion Collisions

    Jiaxing Zhao🇩🇪 · Taesoo Song🇩🇪 · Elena Bratkovskaya🇩🇪 · Joerg Aichelin🇫🇷

    The two-particle correlation function measured in femtoscopic analyses provides access to the interaction potentials between emitted particles. This offers a unique opportunity to investigate interactions among charmed mesons and to explore the nature of possible exotic hadronic states. In this Letter, we study femtoscopic correlations of various charmed-meson pairs in relativistic heavy-ion collisions. The dynamical evolution of the system and charm hadron production are described within the Parton-Hadron-String Dynamics (PHSD) transport approach, while the correlation functions are computed using the Correlation Analysis Tool using the Schrödinger equation (CATS). We demonstrate that heavy-ion collisions provide a significantly more favorable environment than collisions for accessing charmed meson femtoscopic correlations. This arises from enhanced charm-quark production, reduced relative momenta due to in-medium energy loss, and a strong suppression of initial-state correlations. Our results indicate that femtoscopic measurements in heavy-ion collisions offer a sensitive probe of charmed meson interactions and possible hadronic molecular states.

    Comments:
    6 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2605.31527 [pdf]
    0 citations

Affiliations

first authorsco-authorsvia INSPIRE