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Nuclear Theory·nucl-th

Monday·August 3, 2026

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    Intruder structure, deformation, and strengths in from an ab initio perspective

    Mark A. Caprio

    The semimagic nucleus lies just above the island of inversion, raising the possibility of low-lying intruder states and associated deformation. Through ab initio no-core configuration interaction calculations, we shed light on the role of intruder structure, quadrupole deformation, and Elliott SU(3) symmetry in . The results also highlight the influence of mixing between normal and intruder states on the strengths of the transitions from the first two states.

    nucl-th0 citations
  2. 02

    Two unitary limits in low-energy -wave neutron scattering on superfluid nuclei

    Yoshihiko Kobayashi · Masayuki Matsuo

    Low-energy -wave scattering in weakly bound superfluid nuclei is strongly influenced by pairing correlations. In this work, we present an analytical study of low-energy -wave quasiparticle scattering within the coordinate space Hartree-Fock-Bogoliubov framework using a schematic square-well model. Analytical expressions for the phase shift, elastic cross section, scattering length, and effective range are derived in a unified manner. We demonstrate that pairing correlations give rise to two distinct unitary limits, characterized by the divergence of the scattering length. One corresponds to the particle-like unitary limit, which persists even without pairing and is well described by the effective range expansion. The other is a pairing-induced hole-like unitary limit associated with quasiparticle resonances, leading to a breakdown of the effective range expansion. These results clarify the validity of the effective range expansion and highlight the essential role of resonance poles in describing low-energy -wave quasiparticle scattering in superfluid nuclei.

    nucl-th0 citations
  3. 03

    Nuclear mass staggering explains missing stable technetium and promethium

    Daiki Nishimura · Takumi Hasegawa · Rinku Prajapat

    Technetium (Tc) and promethium (Pm) are the only elements that lack stable isotopes in the range up to bismuth, a long-standing puzzle in physics and chemistry. We treat this absence as a problem of selecting the lowest-mass integer proton number Z in beta-stable isobaric chains with odd mass number A. Three-point mass parabolas identify two-unit jumps in the local minimum, whereas a five-point decomposition separates the smooth quadratic component from odd-Z/odd-N mass staggering, defined here as the mass shift of odd-Z isobars relative to neighboring odd-N isobars. With this decomposition, a fitted bulk-plus-shell mass model reproduces the smooth trend and shell-driven bending near magic numbers, including conventional shell-closure skips. This model, however, does not include odd-Z/odd-N staggering and cannot account for the Tc and Pm skips. The separated odd-Z/odd-N staggering remains positive across the Tc and Pm regions and is large enough for the lowest-mass integer-Z sequence to skip Tc and Pm. Shell-model occupation analysis suggests that this regional staggering reflects an orbital-dependent tensor-force monopole effect in the proton-neutron interaction. We identify tensor-force-driven odd-Z/odd-N mass staggering as the origin of the Tc and Pm skips in the odd-A sequence of lowest-mass isobars.

    nucl-th0 citations
  4. 04

    Revisiting the Equation-of-Motion Method: A Universal Framework for Correlated Quantum Systems

    Andrea Porro

    A general implementation of the equation-of-motion (EOM) formalism for correlated many-body states is presented and applied to the description of collective excitations in atomic nuclei. While EOM approaches are traditionally formulated on top of independent-particle reference states, the present work extends the method to correlated reference states generated by modern many-body solvers. This formulation enables a consistent treatment of ground-state correlations and excited-state dynamics within a unified framework. Particular emphasis is placed on collective nuclear excitations employing chiral nuclear Hamiltonians in an ab initio context. The approach is motivated by the renewed interest in EOM techniques across several fields, including quantum chemistry and quantum computing, where they provide efficient and systematically improvable descriptions of excitation spectra. The present results demonstrate that the EOM framework offers a flexible and powerful tool for the microscopic description of nuclear spectroscopy beyond the traditional mean-field paradigm.

    nucl-thcond-mat.str-elphysics.chem-phquant-ph0 citations
  5. 05

    Explicitly on-shell currents in relativistic mean field models

    Alexis Nikolakopoulos🇺🇸 · Ryan Plestid🇨🇭

    Relativistic mean field models are a useful tool for modeling semi-leptonic scattering and photo production on nuclei. When using free-nucleon currents, it is often claimed that there exist so-called ``off-shell ambiguities''. Here we show that when the current is defined in terms of free-nucleon creation and annihilation operators, all ambiguities related to on-shell vs. off-shell Dirac algebra disappear. Genuine ambiguities persist because the current itself depends on the mean field responsible for nuclear binding; these would be fixed if a consistent background-field dependent current were used. As applications, we consider elastic scattering from a nucleus, and (very large) ambiguities that were previous reported in the literature in the context of coherent pion photoproduction. We explain how these ambiguities are removed by the procedure introduced herein.

    nucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE