Nuclear Theory·nucl-th

Wednesday·June 10, 2026

18 papers—10 primary·8 cross-listed

01
[Submitted on 8 Jun 2026]
Thermodynamic versus Dynamical Description of the Neutron-Star Crust-Core Instability: Implications for Crustal Observables
Athul Kunjipurayil🇺🇸 · J. Piekarewicz🇺🇸
We investigate the crust-core transition in neutron stars using both thermodynamic and dynamical descriptions of the instability. In the thermodynamic approach, the transition is identified through the vanishing of a generalized incompressibility coefficient signaling the onset of a bulk spinodal instability. In contrast, the dynamical approach based on the relativistic random-phase approximation (RPA) incorporates Coulomb screening and finite-size effects that determine the instability at finite wavelength. Using a family of covariant energy density functionals spanning a broad range of symmetry-energy slopes, we show that the dynamical treatment systematically predicts lower transition densities and pressures compared to the thermodynamic approach. We further demonstrate that the RPA instability develops at a characteristic length scale set by the competition among bulk, Coulomb, and surface effects. Most importantly, we show that these differences propagate directly into neutron-star observables. Because the thermodynamic approach predicts larger transition pressures, it generates thicker crusts and significantly larger crustal fractions of the stellar moment of inertia than the dynamical-RPA framework -- with important implications for the interpretation of pulsar glitches and other crust-sensitive neutron-star observables.
Comments:
11 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2606.10090 [pdf]
1 citation
02
[Submitted on 8 Jun 2026]
Determining universal spectra from probability distributions
Charles Kacir · Joseph Moscoso · Amy Nicholson · Thomas R. Richardson · Cade Rodgers
The probability distribution of a two-particle correlation function computed over background auxiliary field configurations, used to generate the interactions, has been shown to inform about the spectra of universal $n$ -body clusters [1]. Here, we utilize two approaches, a numerical lattice computation and an analytic expansion in the limit of large numbers of identical species, in an attempt to refine the initial predictions. Exploratory calculations in these directions are presented, and future investigations laid out.
Comments:
Proceedings from the ECT* Workshop "Universality in strongly- interacting systems: from QCD to atoms", June 2025
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat)
arXiv:
2606.10128 [pdf]
0 citations
03
[Submitted on 8 Jun 2026]
Charm quark production in heavy-ion collisions as a signature of pre-equilibrium
Maurice Coquet🇨🇭 · Thomas Faure🇫🇷 · Sören Schlichting🇩🇪 · Mika Spier🇫🇷 · Michael Winn🇫🇷
The relative abundances and kinematic distributions of hadrons containing (anti)charm quarks are key observables for deconfinement, heavy-quark diffusion and hadronization in heavy-ion collisions. The production of (anti)charm quarks is commonly associated to the initial hard scatterings in hadronic collisions. Based on previous studies on dilepton production, we evaluate the (anti)charm quark production from the pre-equilibrium phase. A non-negligible contribution to the overall charm quark production is found albeit large theoretical uncertainties are limiting factors. We conclude that precise total charm production measurements combined with progress on charm production calculations from the initial hard scatterings can be used to infer information on the pre-equilibrium stage.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.10206 [pdf]
0 citations
04
[Submitted on 8 Jun 2026]
Nonflow Subtraction Beyond Two-Particle Correlations
Zaining Wang🇨🇳 · Jiangyong Jia🇺🇸 · Jinhui Chen🇨🇳 · Shengli Huang🇺🇸 · Chunjian Zhang🇨🇳 · Zhengxi Yan🇺🇸
Establishing collective flow in small collision systems is crucial for pinning down the minimum conditions for quark-gluon plasma (QGP) formation. In two-particle correlations, nonflow has been subtracted with good control, pushing the reach of flow measurements down to very small particle multiplicities $N$ . However, the multi-particle nature of collectivity has not been established in the same $N$ regime, because the residual nonflow surviving the subevent procedure in multi-particle cumulants has never been quantified. We develop a general nonflow subtraction framework for $m$ -particle cumulants, built around the approximate $1/ N^{m - 1}$ scaling of nonflow in the independent-source picture. Correlators containing $v_{1}$ serve as clean nonflow estimators, since the $p_{T}$ -integrated dipolar flow nearly vanishes. Using \HIJING{} as a controlled nonflow-only environment, we test the subtraction for three target observables ( $⟨ v_{2}^{2} ⟩$ , $⟨ v_{2}^{2} δ p_{T} ⟩$ , and $c_{2} {4}$ ) in O+O and $d$ +Au at $s_{NN} = 5.36$ TeV and 200 GeV. Most of the nonflow is removed, with residual fractions typically within 20--30% when converted to the two-particle level, though the best estimator differs across the three targets. We identify a multiplicity-reweighting correction, previously overlooked in two-particle correlations, that explains the long-standing undersubtraction of the naive $1/ N$ -scaling method; its impact grows as a power of the correlator order. The framework gives a systematic route to nonflow subtraction beyond two-particle correlations, broadening the class of multi-particle observables accessible to the small-system flow program.
Comments:
18 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.10258 [pdf]
2 citations
05
[Submitted on 9 Jun 2026]
Global polarization of $Λ$ , $Ξ^{-}$ , and $Ω^{-}$ hyperons in Au+Au collisions at RHIC BES-II energies
Gen-Hui Li🇨🇳 · Cong Yi🇨🇳 · Xiang-Yu Wu🇨🇦 · Shi Pu🇨🇳 · Guang-You Qin🇨🇳
We investigate the global spin polarization of $Λ$ hyperons and the multi-strange hyperons $Ξ^{-}$ and $Ω^{-}$ in Au+Au collisions across the RHIC Beam Energy Scan II (BES-II) energy range, $s_{N N} = 7.7$ -- $27$ GeV. The polarization is computed using the modified Cooper--Frye formula, which includes contributions from thermal vorticity, the thermal shear tensor, and the gradient of the baryon chemical potential, combined with the (3+1)-dimensional viscous hydrodynamic framework CLVisc with SMASH initial conditions. We present the global polarization as a function of collision energy, centrality, transverse momentum, and rapidity. We find that the global polarization of $Ω^{-}$ is systematically larger than those of $Λ$ and $Ξ^{-}$ because of its larger spin quantum number, but it remains below the central value of the recent STAR measurement. This discrepancy may suggest that additional mechanisms, such as spin correlations among strange quarks inside the $Ω^{-}$ , could contribute to the observed $Ω^{-}$ polarization. We also find that the global-polarization splitting between hyperons and anti-hyperons increases toward lower collision energies and is dominated by the chemical-potential-gradient contribution.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.10341 [pdf]
0 citations
06
[Submitted on 9 Jun 2026]
Neural-network solution of subtracted three-body Faddeev integral equations near the Efimov limit
Lucas A. Souza🇧🇷
We apply a deep-neural-network (DNN) ansatz to the symmetrized spectator vector of the subtracted three-body Faddeev integral equation for identical bosons near the Efimov limit. The network is trained by minimizing the residual of the discretized integral equation, while the positive binding scale associated with the three-body energy is treated as a trainable parameter. Deterministic diagonalization of the same discretized kernel is used only as an a posteriori numerical benchmark. As preliminary validation, the neural-solver strategy is tested on the analytically solvable hydrogen radial problem. At unitarity, the DNN reproduces the Efimov ground-state binding scale with a DNN--deterministic deviation of $0.022%$ , while the first excited state is recovered to $0.002%$ . The deterministic solver recovers the universal Efimov scaling ratio $e^{2 π / s_{0}} ≃ 515.03$ , and the neural method traces the bound-state branches as a function of the inverse scattering length $1/ a$ by continuation from the unitary solution. These results indicate that DNN-based residual minimization can provide a compact and differentiable representation of a renormalized few-body integral-equation solution in a regime governed by discrete scale invariance.
Subjects:
Nuclear Theory (nucl-th); Mathematical Physics (math-ph); math.MP (math.MP); Quantum Physics (quant-ph)
arXiv:
2606.10343 [pdf]
Few Body Syst.(2026)·0 citations
07
[Submitted on 9 Jun 2026]
Sequential Clusterization of Light Nuclei and Hypernuclei in Heavy-Ion Collisions within a Wigner Function Coalescence Framework
Junyi Han🇨🇳 · Yue-Hang Leung🇩🇪 · Jiaxing Zhao🇩🇪 · Yingjie Zhou🇩🇪 · Norbert Herrmann🇩🇪 · Yaping Wang🇨🇳
We investigate the formation of light nuclei and hypernuclei in Au+Au collisions at $s_{N N} = 3 GeV$ within a coalescence framework embedded in the microscopic N-body Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) transport model. The Wigner phase-space distributions employed in the coalescence calculation are constructed from realistic $N$ -body wave functions obtained by solving the Schrödinger equation in the hyperspherical harmonics formalism, providing a solid and parameter-free description of nuclear clusters and hypernuclei. By comparing calculated rapidity distributions with STAR data, we extract species-dependent coalescence times, revealing a non-universal formation pattern among different clusters. The resulting yields and kinematic distributions of light nuclei and hypernuclei are systematically analyzed and shown to be sensitive to the underlying wave-function structure and formation time. In addition, we explore cluster-nucleon formation channels for $A = 4$ systems. These additional channels improve the description of $^{4} He$ and $_{Λ}^{4} H$ yields and help address the underestimation of $A = 4$ cluster production in theoretical approaches. Finally, we provide predictions for heavier hypernuclei, including $_{Λ}^{5} He$ and $_{ΛΛ}^{5} He$ , which are of interest for future experimental measurements.
Comments:
13 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2606.10441 [pdf]
0 citations
08
[Submitted on 9 Jun 2026]
Simultaneous $α β$ Decay: A New Mode of Nuclear Instability
Wenqiang Zhang🇨🇳 · Chong Qi🇸🇪
We propose simultaneous $α β$ decay as a novel mode of nuclear instability that involves the strong and weak interactions in a single quantum transition. We develop a theoretical framework to predict its branching ratios and $α$ -energy spectra, establishing exclusive and inclusive criteria based on whether the individual $α$ and $β$ channels are closed or open. A global survey of the nuclear chart identifies five exclusive $α β^{-}$ candidates, all predicted to be experimentally inaccessible, and ranks the leading inclusive candidates for both the $α β^{-}$ and $α β^{+}$ modes. Remarkably, six of the top $α β^{+}$ candidates coincide with known $β$ -delayed- $α$ precursors. The observed $α$ spectra are naturally accounted for by simultaneous $α β^{+}$ emission, suggesting direct decay as the dominant underlying mechanism. Our findings establish simultaneous $α β$ decay as a distinct radioactive process and a sensitive probe of the interplay between the strong and weak interactions.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.10567 [pdf]
0 citations
09
[Submitted on 9 Jun 2026]
Gaussian vs. Real Wavefunction of Nuclear Clusters and Hypernuclei
Jiaxing Zhao🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪
We compare realistic $N$ -body wave functions obtained from solutions of the Schrödinger equation with Gaussian ansätze constrained to the same rms radius. The microscopic wave functions exhibit significantly broader spatial distributions, revealing pronounced non-Gaussian structures. In addition, we investigate possible production channels for $A = 4$ clusters using a phenomenological two-body interaction. This study provides a potential mechanism that may help alleviate the underestimation of $A = 4$ cluster yields in theoretical models compared to experimental data.
Comments:
Contribution to: SQM2026
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2606.11008 [pdf]
1 citation
10
[Submitted on 9 Jun 2026]
Quantum Monte Carlo calculations of Zemach moments in $A \leq 9$ nuclei
Garrett B. King🇺🇸 · Sonia Bacca🇩🇪 · Graham Chambers-Wall🇺🇸 · Alex Gnech🇺🇸 · Saori Pastore🇺🇸 · Maria Piarulli🇺🇸 · Robert B. Wiringa🇺🇸
Modern atomic spectroscopy has reached a level of precision at which nuclear-structure effects can no longer be neglected and must be quantified reliably. In particular, hyperfine splittings depend on the Zemach radius, which encodes the convolution of the nuclear charge and magnetization distributions. The third electric Zemach moment provides a related finite-size measure and enters the elastic two-photon-exchange contribution to the Lamb shift in muonic atoms. Here, we compute Zemach radii and other electromagnetic moments for light nuclei using quantum Monte Carlo techniques within modern \textit{ab initio} nuclear theory. Using Norfolk two- and three-body interactions derived within chiral effective field theory, we assess the model dependence and study the role of two-body currents. For $^{6}$ Li, we obtain a Zemach radius larger than that extracted from atomic measurements, consistent with recent calculations, confirming that the discrepancy is not an artifact of the nuclear model. For $^{9}$ Be, our results agree with experiment; the discrepancy of previous phenomenological evaluations is traced to a model-dependent input for the magnetic radius.
Comments:
2 figures, 9 pages
Subjects:
Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2606.11153 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE