Nuclear Theory·nucl-th

Monday·August 3, 2026

9 papers—5 primary·4 cross-listed

01
Intruder structure, deformation, and $E 2$ strengths in $^{14} C$ from an ab initio perspective
Mark A. Caprio
The semimagic nucleus $^{14} C$ lies just above the $N = 8$ 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 $^{14} C$ . The results also highlight the influence of mixing between normal and intruder states on the strengths of the $E 2$ transitions from the first two $2^{+}$ states.
nucl-th0 citations
02
Two unitary limits in low-energy $s$ -wave neutron scattering on superfluid nuclei
Yoshihiko Kobayashi · Masayuki Matsuo
Low-energy $s$ -wave scattering in weakly bound superfluid nuclei is strongly influenced by pairing correlations. In this work, we present an analytical study of low-energy $s$ -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 $s$ -wave quasiparticle scattering in superfluid nuclei.
nucl-th0 citations
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
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
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
06
Algebraic Diagrammatic Construction of the Multichannel Dyson Equation
Thibault Demartini🇫🇷 · J. Arjan Berger🇫🇷 · Guillaume Blanchon🇫🇷 · Thomas Duguet🇫🇷 · Denis Lacroix🇫🇷 · Pina Romaniello🇫🇷 · Vittorio Somà🇫🇷
The multichannel Dyson equation (MCDE) was recently introduced as a new approximation scheme to compute the one-body Green function in many-body systems, as reported by Riva et al. in Physical Review Letters, volume 131, article 216401, published in 2023. The physical content of this novel approximation scheme is further clarified by recovering it from an extended version of the algebraic diagrammatic construction (ADC) truncation scheme. It is thus demonstrated that the MCDE approximation lies in between the so-called ADC(2) and ADC(3) truncations of the dynamical self energy. Building on this clarification, the MCDE approximation is tested on the periodic one-dimensional Hubbard model with 4, 6, and 8 site lattices and shown to deliver an improved treatment over ADC(2) of both the quasiparticle peaks and the so-called satellites in the spectral strength distribution.
↳ cond-mat.str-elnucl-th0 citations
07
Transcorrelated Random-Phase Approximation
Abdallah Ammar · Enzo Monino · Anthony Scemama · Emmanuel Giner · Pierre-François Loos
We extend the random-phase approximation (RPA) to the non-Hermitian transcorrelated (TC) Hamiltonian, which explicitly includes three-body interactions generated by a Jastrow correlation factor. We consider both the direct RPA (dRPA) and RPA with exchange (RPAx). We apply the resulting TC-dRPA and TC-RPAx methods to calculate ground-state correlation energies and vertical excitation energies for atoms (\ce{He} and \ce{Ne}) and small molecules (\ce{H2O}, \ce{NH3}, \ce{CH4}, and \ce{H2CO}). For ground-state correlation energies, the TC treatment substantially improves accuracy and accelerates basis set convergence, reducing errors by nearly an order of magnitude relative to conventional RPA calculations. By contrast, it yields only marginal improvements in vertical excitation energies. We attribute this limited effect to the ground-state optimization of the Jastrow factor, which does not adequately capture the distinct electronic character of excited states. These results establish TC-RPA as an accurate and computationally efficient approach to ground-state energetics, while highlighting the need for state-specific Jastrow optimization to achieve reliable descriptions of excited states.
↳ physics.chem-phcond-mat.mtrl-scicond-mat.str-elnucl-th0 citations
08
Weak Bose-Einstein condensation in a rigidly rotating magnetized charged Bose gas
E. Siri🇮🇷 · N. Sadooghi🇮🇷
We investigate the weak Bose-Einstein condensation (BEC) scenario of a noninteracting charged Bose gas simultaneously subjected to a strong magnetic field and rigid rotation. Using standard methods of finite-temperature quantum field theory and the generalized Fock-Schwinger formalism, we derive the corresponding thermodynamic potential in the nonrelativistic and lowest Landau level approximations. An appropriate modification of the effective chemical potential yields a consistent thermodynamic description and naturally introduces a magnetorotational fugacity. Within the high-temperature approximation, rigid rotation enters the thermodynamics solely through the Tolman-Ehrenfest local temperature. We demonstrate that rigid rotation does not qualitatively modify the weak BEC scenario induced by Landau quantization. The magnetorotational fugacity remains below unity throughout the phenomenologically relevant temperature range, while the continuous evolution of the ground state population and the absence of a singularity in the specific heat provide complementary signatures of the persistence of weak BEC. We further study the thermodynamic properties of the system under conditions relevant to quark-gluon plasma and neutron-star matter. We show that rotational effects are much more pronounced in the former. Our analysis reveals a new magnetic response to rigid rotation: while magnetic fields enhance diamagnetism, rotation drives it toward paramagnetism. This behavior reflects a competition between magnetic quantization and rotational orbital motion, emphasizing the role of rotation in shaping the magnetic response of bosonic matter.
↳ hep-phnucl-th0 citations
09
Nonlinear polarization effects on plasma screening for thermonuclear reactions
Hanxiang Huang · Binbing Wu · Zhengfeng Fan · Congzhang Gao · Jie Liu · Baisong Xie
We investigate two-center plasma screening effects on thermonuclear reactions of D-T, p- $^{11}$ B, and $^{12}$ C- $^{12}$ C, spanning from classical to degenerate regimes. The two-center screening potential is obtained within a finite-temperature Thomas-Fermi-Dirac framework, capturing two-ion correlations as the leading-order many-body effect. Combining the resulting screened Coulomb potential with a complex Woods-Saxon nuclear potential, we solve the stationary Schrödinger equation to obtain the fusion tunneling probabilities and the corresponding reaction rates. Compared to Debye-Hückel results, the present screening potential is stronger in weakly coupled and weakly degenerate regimes but weaker in strongly coupled and strongly degenerate regimes. Consequently, the fusion enhancement factors are amplified in the former but suppressed in the latter. An underlying interplay between two mechanisms is identified: the nonlinear polarization of ions tends to reduce the screening effect, whereas the nonlinear polarization of electrons tends to enhance it. This subtle competition is governed by the plasma coupling strength and degeneracy. These findings highlight that a two-center treatment is important for predicting fusion rates in dense plasmas.
↳ physics.plasm-phnucl-th0 citations

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first authorsco-authorsvia INSPIRE