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Nuclear Theory·nucl-th

Wednesday·August 13, 2025

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 11 Aug 2025]

    The DNA of nuclear models: How AI predicts nuclear masses

    Kate A. Richardson🇺🇸 · Sokratis Trifinopoulos🇺🇸 · Mike Williams🇺🇸

    Obtaining high-precision predictions of nuclear masses, or equivalently nuclear binding energies, , remains an important goal in nuclear-physics research. Recently, many AI-based tools have shown promising results on this task, some achieving precision that surpasses the best physics models. However, the utility of these AI models remains in question given that predictions are only useful where measurements do not exist, which inherently requires extrapolation away from the training (and testing) samples. Since AI models are largely black boxes, the reliability of such an extrapolation is difficult to assess. We present an AI model that not only achieves cutting-edge precision for , but does so in an interpretable manner. For example, we find that (and explain why) the most important dimensions of its internal representation form a double helix, where the analog of the hydrogen bonds in DNA here link the number of protons and neutrons found in the most stable nucleus of each isotopic chain. Furthermore, we show that the AI prediction of can be factorized and ordered hierarchically, with the most important terms corresponding to well-known symbolic models (such as the famous liquid drop). Remarkably, the improvement of the AI model over symbolic ones can almost entirely be attributed to an observation made by Jaffe in 1969 based on the structure of most known nuclear ground states. The end result is a fully interpretable data-driven model of nuclear masses based on physics deduced by AI.

    Comments:
    19 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); cs.AI (cs.AI); Machine Learning (cs.LG); Nuclear Experiment (nucl-ex)
    arXiv:
    2508.08370 [pdf]
    3 citations
  2. 02

    [Submitted on 12 Aug 2025]

    In-medium similarity renormalization group for a pairing-plus-particle-hole model

    L. H. Chen · Y. G. Yao · B. C. He

    We benchmark two implementations of the in-medium similarity renormalization group (IMSRG) method, IMSRG(2) and IMSRG(2*), for the low-lying states of a pairing-plus-particle-hole model with varying numbers of fermions. In IMSRG(2), all operators are truncated up to the normal-ordered two-body terms, whereas IMSRG(2*) includes an additional term to partially account for higher-body contributions. The results are compared against exact solutions. We find that IMSRG(2*) consistently outperforms IMSRG(2) for both ground and excited states, although achieving convergence for excited states remains more challenging in strongly correlated systems than for the ground state.

    Comments:
    7 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2508.08595 [pdf]
    PRC(2026)·0 citations
  3. 03

    [Submitted on 12 Aug 2025]

    Impact of shape coexistence on the symmetric to asymmetric fission mode transition in Th isotopes

    Shengyuan Chen · Zeyu Li · Minghui Zhou · Zhipan Li

    We study the evolution of fission modes along the Th isotopic chain using a microscopic framework combining the time-dependent generator coordinate method and finite-temperature covariant density functional theory. Theoretical fission fragment charge distributions agree well with experiments, and reveal a rapid symmetric-to-asymmetric transition from to 234. By analyzing the collective potential energy surfaces and time evolution of collective probability density distributions, we demonstrate that this fission mode transition is strongly correlated with the rapidly deepening asymmetric fission valley a phenomenon driven by the reduction of deformation energies of both the heavy and light fragments formed in the asymmetric fission valley. Further analysis attributes the decrease of light-fragment deformation energies to the onset of a coexisting large-deformed minimum in neutron-rich Kr and Sr isotopes (dominated isotopes for light asymmetric peak), which arises from a deformed proton shell closure near . Notably, we identify, for the first time, the pivotal role of the light fragment and its shape coexistence structure on the fission mode transition in Th isotopes in a fully microscopic framework.

    Comments:
    7 pages, 7 figures, Submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2508.08616 [pdf]
    PRC(2026)·2 citations
  4. 04

    [Submitted on 12 Aug 2025]

    Spacetime Curvature as a Probe of Exotic Core Phases in Neutron Stars within Modified Gravity

    Sayantan Ghosh🇮🇳 · Bharat Kumar🇮🇳 · Subhash Mahapatra🇮🇳

    In this study, we investigate the effect of Energy-Momentum Squared Gravity (EMSG) on the curvature of neutron stars (NSs) by using three relativistic mean-field (RMF) equations of state (EOSs) and three hadron-quark phase transition (HQPT) EOSs. Neutron stars, with their extreme densities and strong gravitational fields, provide an ideal laboratory for testing General Relativity (GR) in the high-curvature regime and for exploring possible deviations via modified gravity. EMSG extends GR by including nonlinear terms involving the energy-momentum tensor, characterized by a coupling parameter . We focus on the Kretschmann, Ricci, and Weyl curvature scalars, analyzing their dependence on baryon density and radial coordinate for varying values of . Our results indicate that EMSG can significantly alter the curvature profiles of neutron stars. In particular, the magnitude of both Weyl and Kretschmann scalars increases (decreases) for a positive (negative) EMSG parameter, with the former exhibiting a larger dependence. Similarly, the surface curvature (SC) is notably affected by . Interestingly, we further observe distinct discontinuities in the curvature profiles at hadron-quark phase transitions, especially in the soft and intermediate HQPT models. These signatures may provide observable imprints of exotic core phases in neutron stars.

    Comments:
    Comments are welcome
    Subjects:
    Nuclear Theory (nucl-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2508.08866 [pdf]
    PRD(2026)·6 citations
  5. 05

    [Submitted on 11 Aug 2025] (cross-list from hep-ph)

    Nucleon Energy Correlators as a Probe of Light-Quark Dipole Operators at the Electron-Ion Collider

    Yingsheng Huang🇨🇳 · Xuan-Bo Tong🇫🇮 · Hao-Lin Wang🇨🇳

    We propose nucleon energy correlators (NECs) as a novel framework to probe electroweak light-quark dipole operators in deep inelastic scattering with an unpolarized nucleon. These operators encode chirality-flipping interactions, whose effects are usually quadratically suppressed in unpolarized cross sections. We construct a chiral-odd quark NEC that accesses quark transverse spin via azimuthal angle asymmetries in the energy flow of the target fragmentation region. These asymmetries serve as clean and powerful observables, enabling linear constraints on the quark dipole couplings. Unlike existing methods, our approach requires neither polarized nucleon beams nor final-state hadron identification, relying instead on fully inclusive calorimetric measurements. This work establishes one of the first applications of energy correlator observables to new physics searches and opens a promising direction for precision studies of chirality-flipping effects at electron-ion colliders.

    Comments:
    8 pages (main text) plus 11 pages (supplemental material), 13 figures, 1 table; version published in PRL
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2508.08516 [pdf]
    PRL(2026)·14 citations
  6. 06

    [Submitted on 12 Aug 2025] (cross-list from nucl-ex)

    On the High Excitation 7 De-exciting States in Si

    J. B. Natowitz · X. G. Cao · A. Bonasera · T. Depastas

    A direct comparison and analysis of published spectra for the 7 disassembly of Si projectiles excited in collisions with C at 35 MeV/u reveals significant agreement in the derived excitation energies of high excitation energy resonances observed in two different experiments, in contrast to some earlier conclusions reported in the literature. Many of the observed resonances have excitation energies consistent with those arrived at in recent theoretical investigations explicitly predicting the excitation energies and spins of toroidal nuclei. An AI-assisted application of well-established statistical filtering techniques reveals identical structures in all spectra investigated. Some additional peaks are observed. The possibility that they correspond to other favored geometries is discussed.

    Comments:
    7 pages, 4 figures, 2 tables
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2508.08878 [pdf]
    0 citations
  7. 07

    [Submitted on 12 Aug 2025] (cross-list from hep-ph)

    Quarkonium in a QCD medium with momentum-dependent relaxation time

    Sunny Kumar Singh🇮🇳 · Samapan Bhadury🇵🇱 · Ritesh Ghosh🇺🇸 · Manu Kurian🇮🇳

    In this study, we explore the properties of quarkonia in a hot QCD medium using a newly proposed collision kernel that consistently incorporates the particle's momentum dependence into the relaxation time scale of the medium. The longitudinal component of the gluon self-energy, along with the Debye screening mass, is computed within the one-loop hard thermal loop framework by incorporating non-equilibrium corrections. A modified kinetic theory with an extended relaxation time approximation is employed to model the non-equilibrium dynamics of the QCD medium. The sensitivity of the heavy quarkonia potential to the momentum dependence of the relaxation time is studied. Further, we studied the binding energy and thermal width of quarkonia states within this new kinetic theory. Sizable variations in the temperature behavior of these quantities are observed in comparison with the standard relaxation time approximation method due to the particle momentum dependence on the relaxation timescale of the QCD medium. Our findings highlight that accounting for the microscopic nature of the collision timescale is crucial for understanding the quarkonium behavior in a QCD medium.

    Comments:
    27 pages, 6 multi-panel figures, version accepted in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2508.09108 [pdf]
    PRD(2025)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE