PaperPanorama

Nuclear Theory·nucl-th

Thursday·August 27, 2026

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    Spectroscopy of 211,213,215Pb isotopes and seniority properties

    Larry Zamick · Praveen Srivastava

    We first consider lead isotopes with valence neutrons in the g9/2shell. We especially compare 211Pb (n=3), 213Pb (n=5) and 215Pb (n=7), 213Pb being at mid-shell. Motivated by the fact the J = 21/2+ and J =3/2+ states are pure seniority v=3 states for both n=3 and n=5, we compare the energy splitting E(J=21/2+)-E(J=3/2+) for various interactions. We then discuss the position of the lowest J=3/2+ state in both n=3 and n=5, although, this state has not been found experimentally. Calculations with configurations beyond g9/2 are also considered. We next address the fact that the J=21/2+ state is isomeric for both n=3 and n=5.

    nucl-thIJMPE(2026)·0 citations
  2. 02

    Joint cluster-EFT analysis of N -delayed spectra and -C scattering

    Jubin Park · Myeong-Hwan Mun · Shung-Ichi Ando

    The -delayed decay (BDAD) of N probes the -wave -C continuum relevant to the low-energy transition of CO. We analyze the spectra of Azuma \textit{et al.} and Tang \textit{et al.} within cluster effective field theory, fitting each independently together with the same elastic-scattering data. The baseline eight-parameter fits yield for the Azuma spectrum and for the Tang spectrum, substantially improving upon the corresponding fixed-propagator values of 4.06 and 3.56, respectively. The raw simultaneous fit yields , , and for the Azuma, Tang, and elastic-scattering data, respectively. With sector-balanced weighting, the corresponding values are 3.308, 8.993, and 6.466, respectively. Thus, reducing the relative elastic weight improves the BDAD sectors but does not recover the quality of the independent fits. The common strong parameters and normalization ratio remain stable, whereas the fitted weak-current coefficients depend on the objective. The two spectra are separately compatible with a common strong continuum, but the minimal common weak-current amplitude does not reproduce them simultaneously; its fitted coefficients also depend on the objective. These results define the experimental and model sensitivities that must be propagated in a future unified analysis including radiative capture.

    nucl-th0 citations
  3. 03

    Impact of Nuclear Level Density on -Process Rare-Earth Peak Nucleosynthesis

    Hang Xu · Peng-Xiang Du · Jian Li · Dong-Liang Fang

    The rare-earth peak () is a prominent feature of the -process, and previous theoretical studies suggest that it is possibly linked to local nuclear structural effects. However, the nuclear level density (NLD), a physical quantity directly reflecting these properties, has been largely overlooked compared to other structural properties such as nuclear masses. To address this, we perform -process simulations across three astrophysical scenarios using neutron-capture rates derived from six distinct NLD models. Our results reveal that microscopic models yield systematic deviations in NLD relative to phenomenological ones, leading to critical impacts on nucleosynthesis. Specifically, systematic NLD differences in even- nuclei redirect the nuclear flow, accelerating the early formation of the rare-earth peak and temporarily enhancing its magnitude. This underlying structural shift also fundamentally alters the -process sensitivity to the neutron-capture rate, effectively eliminating its dependence on the odd-even nature of protons. Overall, these findings demonstrate that the internal nuclear structure encoded within NLDs can collectively induce a global redirection of the nucleosynthesis pathway, highlighting the critical need for self-consistent microscopic inputs in future simulations.

    nucl-thastro-ph.HE0 citations
  4. 04

    Directional correlations in nuclear charge-radius model residuals enable extrapolation with calibrated uncertainties

    Debodyuti Kar · Soumya Bagchi · Timo Dickel · Rituparna Kanungo

    We identify a pronounced directional anisotropy in the residuals between measured nuclear charge radii and two structurally distinct global models: the phenomenological Weizsäcker--Skyrme formula (WS*) and the microscopic Hartree--Fock--Bogoliubov model (HFB-25). In both cases, the residuals remain correlated over several neutron steps along isotopic chains but decorrelate almost completely after a single proton step along isotonic chains. This common pattern, reinforced by a strong correlation between the two residual fields (), points to a shared deficiency of both global descriptions rather than a model-specific artefact. Motivated by this geometry, we introduce ARCUS (Anisotropic Residual Calibration with Uncertainty Scaling), which applies an anisotropic kernel-regression correction with empirically calibrated prediction intervals. In out-of-fold cross-validation, ARCUS reduces the root-mean-square errors of both WS* and HFB-25 by approximately a factor of two. On an independent, temporally blind test set of 129 nuclei, its prediction intervals retain coverage close to nominal under extrapolation. An isotropic kernel matched to the same cross-validation coverage instead substantially overestimates uncertainties on the blind set, showing that reliable calibration transfer depends on encoding the directional residual structure. In regions with anomalous structure, such as around Ca, ARCUS keeps its prediction intervals wide enough to cover the increased errors, rather than yielding overconfident point predictions. We also extend these calibrated predictions to 1008 unmeasured nuclei near known isotopic chains, ranked by uncertainty to support the future charge-radius measurements.

    nucl-thnucl-ex0 citations
  5. 05

    Evidence for Quartet Binding of Valence Neutrons in He

    Young-Ho Song · Yuan-Zhuo Ma · Dean Lee

    Multimodal neutron superfluidity predicts quartets formed as bound states of two spin-singlet -wave neutron pairs. We present evidence that the four valence neutrons of He realize the finite-system analogue. Quartet binding depends not only on the strength of neutron-neutron attraction but also on the number and symmetry of sufficiently strong attractive pair modes. Pauli blocking limits reuse of the same pair structure, while additional modes can provide extra binding. A partial-wave analysis of the neutron-neutron interaction in Daejeon16 no-core shell-model calculations identifies cooperative pairing and additional attraction as the dominant neutron-neutron contributions to this nonadditive binding, while density cumulants reveal connected four-neutron correlations.

    nucl-thnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE