Nuclear Theory·nucl-th

Tuesday·July 14, 2026

19 papers—13 primary·6 cross-listed

01
Absence of a shell closure in $^{140}$ Sn
Francesca Bonaiti · Bingcheng He · Gaute Hagen · Thomas Papenbrock
There are conflicting theoretical results about the presence of a shell closure in the neutron-rich nucleus $^{140}$ Sn. We address this controversy by performing ab initio computations, using a nuclear interaction from chiral effective field theory that accurately reproduced and predicted low-lying states in doubly magic nuclei. We verify that this interaction accurately reproduces low-lying states in $^{133}$ Sn. We assume that $^{140}$ Sn exhibits a closed $7/ 2^{-}$ neutron subshell beyond $^{132}$ Sn and compute its first excited $2^{+}$ state. The resulting energy is small and this contradicts the assumption.
nucl-thnucl-ex1 citation
02
The Lorentzian geometry of relaxation
Lorenzo Gavassino🇬🇧
We show that relativistic theories with purely relaxational excitation spectra, such as kinetic theory and transient hydrodynamics, naturally endow the dispersion plane ${iω, ik}$ with a Lorentzian geometric structure analogous to that of the Minkowski plane ${t, x}$ . In this picture, timelike future-directed, timelike past-directed, and spacelike directions correspond respectively to relaxation-like, unstable-like, and evanescent-like modes. Under mild structural assumptions on the underlying theory, causality constrains dispersion relations to follow spacelike trajectories on the plane. This geometric viewpoint recasts longstanding problems in relativistic matter physics as elementary geometric ones that can often be solved graphically. As applications, we derive universal constraints on dispersion relations, deviations from time dilation, the observer dependence of spectral hierarchies, the regime of validity of hydrodynamics in boosted frame, the maximal allowed diffusivity and viscosity of relativistic media, and the presence of non-hydrodynamic branch cuts in kinetic theory.
nucl-thgr-qchep-thmath-ph+14 citations
03
Causality and Stability of First-Order Relativistic Spin Hydrodynamics with Conserved Charges
Wei Lu🇨🇳 · Yang Zhong🇨🇳 · Sheng-Qin Feng🇨🇳
We study the causality and stability of first-order relativistic spin hydrodynamics with particle-number conservation. By deriving the complete dispersion relations of linear perturbations around global equilibrium, we find that conserved-charge dynamics modifies the sound sector and introduces additional non-hydrodynamic modes absent in the charge-neutral theory. While the structure of spin relaxation modes remains unchanged, the stability conditions acquire new contributions from charge diffusion and thermodynamic susceptibilities. More importantly, a particle-number-induced mode is shown to violate the causality condition in the short-wavelength limit. We further demonstrate that particle-number conservation does not remove the instability inherent in first-order spin hydrodynamics. These results reveal nontrivial interplay between spin and conserved-charge dynamics and provide important constraints on relativistic spin hydrodynamic theories at finite density.
nucl-thUniverse(2026)·0 citations
04
Emulating Density Functional Theory Calculations via Empirical Interpolation
Daniel Lay · Pablo Giuliani · Kyle Godbey
Nuclear density functional theory (DFT) is a suitable tool for predicting nuclear ground-state and fission properties. Statistical uncertainty quantification is desirable to make those predictions reliable, especially for nuclei far from stability. However, the computational cost associated with describing deformed nuclei in DFT makes such uncertainty quantification a challenge. In many solvers, the main computational bottleneck is the transformation of the wavefunction-dependent operators from coordinate to configuration space. We explore the use of the empirical interpolation method (EIM) to speed up the coordinate-configuration transformations, effectively constructing DFT emulators for ground-state and fission properties. To train and test the emulator we vary the model parameters across their realistic posterior distribution. We consider both a simplified one-dimensional model, and realistic axially-deformed nuclei at the Hartree-Fock-Boguliubov (HFB) level. For realistic calculations, we consider sample nuclei from across the chart, from $A = 60$ up to $A = 254$ , as well as a highly-deformed fission isomer. We construct one emulator for each case, and study the binding energy, quadrupole deformation, and excitation energy of the fission isomer. In all nuclei, for all observables considered, the EIM emulator agrees with the DFT value to the precision of the original DFT calculations, using as few as 100 HFB calculations to build the emulator. For a given nuclear ground state or isomer, the emulator is able to predict all observables simultaneously. The emulator provides an order-of-magnitude speedup over the original solver, making EIM a suitable emulation scheme for DFT, especially when high precision is desired as in model calibration and fission. Thus, the EIM helps make statistical uncertainty feasible, improving the reliability of future predictions.
nucl-th0 citations
05
From hyperon--nucleon interactions to deuteron--hyperon femtoscopy
Jiaxing Zhao🇩🇪
We investigate the low-energy scattering and femtoscopic correlation functions of the $d - Λ$ , $d - Σ$ , and $d - Ξ$ systems within a microscopic folding approach. The effective deuteron--hyperon interactions are constructed by folding the HAL-QCD hyperon--nucleon potentials with the deuteron wave function, while the spin and isospin structures are treated through Wigner- $6 j$ recoupling coefficients. Using the resulting interactions, we calculate the scattering parameters and momentum correlation functions for all spin channels. No bound states are found for the $d Λ$ , $d Σ$ , or $d Ξ$ systems. Nevertheless, the $d Λ$ correlation exhibits a pronounced low-momentum enhancement associated with a large scattering length and a near-threshold pole, whereas the $d Σ$ correlation is suppressed by its predominantly repulsive interaction. The neutral $d Ξ^{0}$ system shows only a moderate enhancement, while the charged $d Ξ^{-}$ correlation is strongly amplified by the attractive Coulomb interaction. We further investigate feed-down effects from $Σ^{0}$ , $Σ (1385)$ , and $Ξ$ decays using Monte Carlo response matrices and demonstrate that these decays clearly modify the observable $d Λ$ correlation. Our results provide quantitative predictions for future femtoscopic measurements and establish deuteron--hyperon correlations as a sensitive probe of hyperon--nucleus interactions.
nucl-thhep-ph0 citations
06
A Lawson-inspired Cycle-Closure Criterion for Deuterium--Tritium Muon-Catalyzed Fusion
Wei Kou · Xurong Chen
Deuterium--tritium muon-catalyzed fusion is limited by a cycle-closure problem: a negative muon must complete enough catalytic cycles before decay or effective alpha sticking removes it from reuse. We formulate a Lawson-inspired criterion for this single-muon cycle. The effective cycle strength is defined as $L_{μ} = Λ_{c} τ_{μ}$ , where $Λ_{c}$ is the effective cycle-completion rate and $τ_{μ}$ is the muon lifetime. Together with the residual effective sticking probability $ω_{S}^{eff}$ , it gives the mean fusion yield per useful muon, $N_{fus, μ} = L_{μ} / (1 + ω_{S}^{eff} L_{μ})$ . Introducing the useful D--T cycle energy $E_{use}$ , the system factor $η_{sys}$ , and the effective muon cost $E_{μ}^{cost}$ , the one-muon gain is $G_{μ} = (η_{sys} E_{use} / E_{μ}^{cost}) N_{fus, μ}$ . This leads to the required cycle strength $L_{μ}^{req} = G_{μ} N_{L} / (1 - ω_{S}^{eff} G_{μ} N_{L})$ , with $N_{L} = E_{μ}^{cost} / (η_{sys} E_{use})$ , and to the conditional sticking boundary $ω_{S}^{eff} < 1/ (G_{μ} N_{L})$ . The criterion separates rate-limited, sticking-limited, and cost-limited regimes in the $(ω_{S}^{eff}, L_{μ})$ plane. When representative historical D--T $μ CF$ anchors are projected onto this plane, they lie in a high-yield region but remain constrained by the effective-sticking boundary under conventional multi-GeV muon-cost accounting. The framework provides a compact diagnostic for assessing whether future improvements act mainly by increasing the effective cycle-completion rate, reducing residual sticking, or lowering the useful cost of delivered muons.
nucl-thnucl-ex0 citations
07
Investigating $J / ψ$ spin alignment in heavy-ion collisions within a two-component transport model
Yida Yang🇨🇳 · Anping Huang🇨🇳 · Baoyi Chen🇨🇳
We investigate the spin alignment of $J / ψ$ mesons in relativistic heavy-ion collisions within a two-component Boltzmann transport model. Starting from the relativistic spin Boltzmann equation, we derive the spin density matrix element $ρ_{00}$ under a non-relativistic approximation for heavy quarks. To interpret the recent ALICE measurements in Pb+Pb collisions, the observed $ρ_{00}$ is described as a $p_{T}$ -dependent mixture of contributions from primordial production and the coalescence process. At forward rapidity, the $p_{T}$ dependence of charmonium $ρ_{00}$ is well reproduced by this two-component mechanism: at low $p_{T}$ , charmonium production is dominated by the coalescence of partially polarized charm quarks induced by thermal vorticity; with increasing $p_{T}$ , primordially produced charmonia become dominant, causing $ρ_{00}$ to approach $1/3$ . To further test this spin alignment mechanism, we provide predictions for the $J / ψ$ $ρ_{00}$ in the mid-rapidity region, which exhibits a distinct $p_{T}$ trend due to the kinematic suppression of the thermal vorticity contribution. This study elucidates the underlying mechanism of $J / ψ$ spin alignment and advances our understanding of heavy quarkonium spin dynamics in strongly interacting matter.
nucl-th0 citations
08
Microscopic Study of Charge Properties in Halo Nuclei
Yun Dong Wang · Hui Hui Xie · Tian Shuai Shang · Peng Xiang Du · Jian Li · Kaiyuan Zhang
Employing the relativistic continuum Hartree-Bogoliubov (RCHB) theory with intrinsic electromagnetic structure corrections, this work primarily investigates the charge properties of halo nuclei along the Ne and P isotopic chains. Our results characterize halo nuclei by an extended tail in the charge density and distinct signatures in the charge form factors at low momentum transfer. Moreover, the higher-order radial moments of nuclear charge density, particularly the eighth moment, exhibit pronounced oscillations, serving as a key indicator of the neutron halo structure. These special features in nuclear charge distributions will serve as key references for identifying halo nuclei.
nucl-thPRC(2026)·0 citations
09
Comparative folding-model study of low-energy elastic scattering and fusion of the $^{12}$ C+ $^{12}$ C and $^{16}$ O+ $^{16}$ O systems
Le Hoang Chien · Dao T. Khoa · Nguyen Hoang Phuc · Doan Thi Loan · Nguyen Tri Toan Phuc
A density dependent nucleon-nucleon interaction (CDM3YR) has been parametrized based on the original M3Y-Reid interaction, to properly reproduce the saturation properties of symmetric nuclear matter (NM) in the nonrelativistic Hartree-Fock calculation, with the energy of NM in a good agreement with the microscopic \emph{ab-initio} results over densities up to three times the saturation density. The real optical potential (OP) of symmetric $^{12}$ C+ $^{12}$ C and $^{16}$ O+ $^{16}$ O systems is then calculated within the double-folding model (DFM), using the realistic densities of $^{12}$ C and $^{16}$ O nuclei and CDM3YR interaction, for the optical model analysis of elastic scattering at low energies and determination of the astrophysical $S$ factor of $^{12}$ C+ $^{12}$ C and $^{16}$ O+ $^{16}$ O fusion in the barrier penetration model. The DFM calculation of the real OP for these two symmetric systems was also done using the original (density independent) M3Y-Reid interaction, and that added by a repulsive core suggested by Esbensen {\it et al.} to explore the impact of medium effects that are effectively encoded in the density dependence of the CDM3YR interaction.
nucl-thPRC(2026)·0 citations
10
Ab initio study of $β$ -decay and pairing in $N = Z$ nuclei
Subhrajit Sahoo · Praveen C. Srivastava
We investigate the $β$ -decay properties of $r p$ -process waiting-point nuclei $^{72}$ Kr, $^{68}$ Se, and $^{64}$ Ge from realistic nuclear forces based on chiral effective field theory. The \textit{ab initio} valence-space in-medium similarity renormalization group method is employed for this purpose to consistently derive Hamiltonians and Gamow-Teller operators from chiral two- and three-nucleon interactions. The calculated half-lives and branching ratios indicate that nearly the entire decay intensity is confined within 1 MeV of excitation energy in the daughter nuclei. We address the isoscalar and isovector pairing and their impact on ground state properties of these waiting-point nuclei, along with several other $N = Z$ systems in the $f p$ -shell. Our results do not provide evidence for an isoscalar condensate or any dominant isovector pairing condensate-like phase in these $N = Z$ nuclei. We present the full $B (GT)$ strength distributions and discuss the influence of pairing correlations on them. The present work provides a microscopic picture of $β$ -decay strengths and pairing in $N = Z$ nuclei far from the stability line.
nucl-thnucl-exPRC(2026)·1 citation
11
Search for the Double Poles of the Scattering Matrix in Light Nuclei
David Cardona Ochoa🇫🇷 · Marek Płoszajczak🇫🇷 · Nicolas Michel🇨🇳
Exceptional points (EPs) are non-Hermitian degeneracies at which two eigenvalues and their eigenvectors coalesce, producing a defective Hamiltonian and a double pole of the $S$ -matrix. Using the coupled-channel Gamow Shell Model with the $ℓ = 1$ spin-orbit strengths as control parameters, we locate and characterize EPs in $^{6} Li$ , $^{7} Li$ , $^{7} Be$ , and $^{8} Be$ , and analyze their imprint on energies, widths, phase rigidity, spectroscopic factors, elastic cross sections, survival probabilities, and spectral functions. The signatures of the EP in scattering and time-domain observables are found to be strongly channel-dependent, and threshold effects play a decisive role in determining the accessibility of the EP in parameter space.
nucl-thquant-phPRC(2026)·0 citations
12
The petit four of color-superconducting phases in proto-neutron star evolution
Selina Kunkel🇩🇪 · Ishfaq Ahmad Rather🇩🇪 · Hosein Gholami🇩🇪 · Marco Hofmann🇩🇪 · Jürgen Schaffner-Bielich🇩🇪
At high densities and moderate temperatures, hadronic matter is expected to undergo a first-order phase transition into a color-superconducting (CSC) state. A proto-neutron star describes the earliest evolutionary stages during the first seconds to minutes after core-collapse supernovae and therefore has the potential to assess the appearance of CSC phases at such high densities and moderate temperatures. To address this, we incorporate proto-neutron star conditions, considering neutrino-trapped and neutrino-transparent ones, into the equation of state including color-superconducting phases in a recently developed RG-consistent NJL model. Since the total baryon number of a proto-neutron star is conserved during its later evolution, tracking stellar configurations from an initial mass of the hot proto-neutron star to the final cold neutron star along isolines of baryon number allows us to investigate whether color-superconducting phases can form at any point along this trajectory. By mapping this multidimensional transition in the hot furnace of a core-collapse supernovae cooling from a neutrino-trapped birth state to a cold, neutrino-transparent final state, we reveal four distinct core evolution scenarios-our "petit four" of proto-neutron star evolution: a delayed collapse from the CSC phase to a black hole, a persistent CSC phase, a vanishing CSC phase, and a fleeting CSC phase. For our specific parameterization of the hadronic and the CSC equation of state, we find that a stable color-superconducting phase can only be sustained in the final cold neutron star for a narrow, high-mass region.
nucl-thastro-ph.HEastro-ph.SR1 citation
13
Ab initio calculations of two-neutrino and neutrinoless double- $β$ decay of $^{48}$ Ca and related Gamow-Teller strength distributions
Zhen Li🇩🇪 · Lotta Jokiniemi🇩🇪 · Achim Schwenk🇩🇪
We present ab initio calculations of two-neutrino double-beta ( $2 ν β β$ ) decay of $^{48}$ Ca and the related Gamow-Teller (GT) strength functions in $^{48}$ Sc using the valence-space in-medium similarity renormalization group (VS-IMSRG) with nuclear interactions and electroweak currents based on chiral effective field theory. We find that the usual $p f$ -shell valence space significantly underestimates the nuclear matrix element (NME) of $2 ν β β$ decay compared to experiment, while an enlarged $d_{3/2} p f$ valence space yields very good agreement with the experimental value without any adjustments. We trace this to an improved description of the involved GT strength distributions, so that the enlarged valence space captures important correlations. The enlarged $d_{3/2} p f$ valence space leads to neutrinoless $β β$ NMEs of $^{48}$ Ca that are twice as large compared to the $p f$ -shell calculation. Our findings suggest that studies with different valence spaces and related GT strengths are important for assessing ab initio NME calculations of heavier $β β$ decays.
nucl-thhep-phnucl-ex2 citations

Affiliations

first authorsco-authorsvia INSPIRE