Nuclear Theory·nucl-th

Friday·September 4, 2026

11 papers—6 primary·5 cross-listed

01
A Practical Partial-Wave Method for Identifying Unstable Light Nucleus Resonances in Heavy-Ion Collisions
Junlin Wu🇨🇳 · Hongchan Li🇨🇳 · Ke Mi🇨🇳 · Yaping Wang🇨🇳 · Guannan Xie🇨🇳
The production of light nuclei in relativistic heavy-ion collisions provides valuable insights into the dynamics of the hot and dense matter created in these extreme environments. While stable light nuclei have been extensively studied, unstable light nuclei being short-lived resonance states remain largely unexplored and offer unique opportunities to probe final-state interactions and the freeze-out conditions. In this paper, we propose a partial-wave method, based on the Lednický--Lyuboshitz framework, to extract resonance signals of unstable light nuclei from two-particle correlation functions measured in heavy-ion collisions. By extending the LL model to higher order partial waves and directly incorporating experimental phase-shift data from low-energy nuclear scattering, our approach avoids the need for model-dependent potential parametrizations and enables a clean decomposition of the resonant partial wave from the non-resonant background. As a demonstration, we apply the method to the $p$ - $^{3}$ He and $p$ - $^{4}$ He systems, corresponding to the $^{4}$ Li and $^{5}$ Li ground-state resonances. Numerical results show that the resonance-induced correlation excess can be effectively isolated, with a peak in the correlation function appearing at $k \approx 72$ MeV/ $c$ for $^{4}$ Li and $k \approx 50$ MeV/ $c$ for $^{5}$ Li, consistent with the known resonance parameters. The extracted transverse momentum spectra and rapidity distributions are presented using the measured proton and light-nuclei spectra from STAR at $s_{N N} = 3$ GeV. The proposed method provides a practical tool for the experimental study of unstable light nuclei in relativistic heavy-ion collisions and can be extended to a broader range of resonance states.
nucl-thhep-ph0 citations
02
Influence of configuration-interaction on isospin impurities and isospin symmetry breaking corrections to superallowed $0^{+} \to 0^{+}$ beta decays
Jakub Wysocki🇵🇱 · Jan Miśkiewicz🇵🇱 · Jagjit Singh🇬🇧 · Wojciech Satuła🇵🇱
The symmetry-conserving density functional theory (DFT)-based no-core configuration-interaction (DFT-NCCI) framework is applied for the first time to investigate the impact of configuration interaction (CI) on the Coulomb (isospin) impurity, $α_{C}$ , in the ground and excited states of $^{10}$ C, $^{10}$ B, and $^{14}$ N, as well as on the isospin-symmetry-breaking (ISB) correction to the superallowed $0^{+} \to 0^{+}$ $β$ decay of $^{10}$ C. We demonstrate, among other findings, that within the DFT-NCCI framework CI has a negligible effect on the ground-state isospin impurities, which are dominated by a single doorway state. In contrast, CI significantly modifies the impurities in excited states, including the isobaric analogue $I = 0^{+}, T = 1$ state in $^{10}$ B. Hence, it also has a non-negligible impact on the ISB correction to the superallowed $β$ decay of $^{10}$ C. Our calculations yield $δ ˉ_{C} = 0.45 (4) %$ when the Coulomb interaction is taken as the sole source of ISB, and $δ ˉ_{ISB} = 0.46 (6) %$ when short-range charge-symmetry-breaking (CSB) terms are included in addition. Hence, no statistically significant dependence of the ISB correction on the short-range CSB interaction is observed for this decay. Comparison with our previous results reveals a strong sensitivity to the nuclear symmetry energy, which governs the strength of the isospin-restoring force and whose value in finite nuclei remains difficult to constrain because of its intricate dependence on the momentum-dependent terms of the effective interaction.
nucl-th0 citations
03
$α$ -decay for superheavy nucleus: The alpha decay energy to the one-fourth power
Jinyu Hu🇨🇳 · Chen Wu
Recently, Sobhani and Luo \cite{sobhani2025unified} proposed a new empirical formula for $α$ decay based on the $Q_{α}^{- 1/4}$ energy dependence, incorporating the proton number $Z$ , neutron number $N$ , and relative neutron excess $I = (N - Z) / (N + Z)$ as primary parameters. In this work, we extend this model by explicitly including the angular momentum of the emitted $α$ particle and the quadrupole deformation of the daughter nucleus. Using this improved formula to evaluate the $α$ -decay half-lives of 400 nuclei yields a root-mean-square (RMS) deviation of 0.97 relative to experimental data. Furthermore, we employ support vector regression (SVR)-taking $Q_{α}^{- 1/4}$ , $N$ , $Z$ , angular momentum, and daughter-nucleus deformation as input features-which further reduces the RMS deviation to 0.56. Finally, we apply both the extended formula and the SVR model to predict the $α$ -decay half-lives of even-even nuclei with $Z = 120$ and $Z = 122$ . The predicted half-lives show good consistency with those from the Sobhani and Poenaru formulas, and both approaches strongly support $N = 184$ as the next neutron magic number.
nucl-th0 citations
04
Reduced-basis method for linear response within nuclear density functional theory
Nobuo Hinohara · Xilin Zhang🇺🇸 · Jonathan Engel🇺🇸
Background: The quasiparticle random-phase approximation (QRPA) within nuclear density functional theory provides a powerful framework for describing collective excitations. Although the finite-amplitude method (FAM) efficiently solves the QRPA problem, repeated calculations for different external-field parameters remain computationally demanding. Purpose: We construct a reduced basis method (RBM)-based emulator for the FAM that treats the complex energy of the external field as a model parameter to efficiently reproduce FAM amplitudes and QRPA eigenmodes. Methods: High-fidelity FAM calculations are performed at a small set of training points in the complex-energy plane. The resulting FAM amplitudes form a non-orthogonal reduced basis. A variational equation yields an emulator that can predict the response at arbitrary complex energies and QRPA eigensolutions without additional full FAM calculations. Results: The RBM emulator accurately reproduces FAM strength distributions in both giant-resonance and low-energy regions when the relevant energy domain is covered by the training set. It also reproduces imaginary QRPA modes associated with shape instabilities of the HFB state. Applied to the $K^{π} = 0^{+}$ mode of rare-earth Dy isotopes in a realistic model space, the emulator reproduces strength distributions and the lowest $0^{+}$ collective states with precision comparable to full FAM calculations, reducing the computational cost by more than an order of magnitude. Conclusions: The RBM provides an efficient and accurate FAM emulator. Its ability to reproduce giant-resonance, low-energy, and imaginary-energy modes at drastically reduced computational cost makes it promising for density-functional optimization, calculations of collective inertia, and large-scale surveys of nuclear collective excitations.
nucl-th0 citations
05
Microscopic Calculation of Electric Quadrupole Effective Charges in Exotic Nuclei
Jia Liu · Yong Peng🇨🇳 · Xiao-Yan Zhu · Xiao-Hua Li🇨🇳 · Wen Luo · Yi-Fei Niu🇨🇳 · Wen-Hui Long
Electric quadrupole ( $E 2$ ) effective charges are evaluated based on the self-consistent relativistic Hartree-Fock single-particle states, with core-polarization corrections resummed to all orders using the Tamm-Dancoff approximation (TDA). Configuration-interaction relativistic Hartree-Fock (CI-RHF) calculations employing the TDA effective charges well reproduce the $B (E 2)$ strength for neon isotopes from stability to the neutron drip line. We find that polarization charges associated with continuum states are significantly quenched due to their extended density distributions and weak coupling to the core, underscoring the critical role of continuum effects in $E 2$ transition evaluations for exotic nuclei. Moreover, the CI-RHF model predicts a suppressed $B (E 2; 2_{2}^{+} \to 0_{2}^{+})$ in $^{30}$ Ne, together with strong in-band $B (E 2)$ strengths of the yrast band, suggesting the coexistence of a nearly spherical excited $0_{2}^{+}$ state and a deformed ground state within the $N = 20$ "island of inversion".
nucl-th0 citations
06
B(E2) Serves as a Robust Signature of N = 32,34 Shell Evolution
Jia Liu · Yi Fei Niu🇨🇳 · Xiao Hua Lia · Wen Luo · Wen Hui Long
Electric quadrupole transition probabilities $B (E 2)$ serve as key probe of nuclear shell evolution, yet anomalous $B (E 2)$ values in exotic nuclei complicate the identification of new magic numbers. In this letter, employing the configuration-interaction relativistic Hartree-Fock model, we demonstrate that effective charges are sensitive to orbital radii, and this orbital dependence is significantly amplified by the halo structure of valence nucleons. This mechanism is critical for reliably describing $E 2$ transitions and understanding the unusual behavior of $B (E 2)$ in exotic nuclei. Our calculations predict reduced $B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ values in $^{52, 54} Ca$ , signaling the emergence of subshell closures at $N = 32$ and 34. Furthermore, the suppressed $B (E 2; 7/ 2_{1}^{-} \to 11/ 2_{1}^{-})$ transition in $^{53} Sc$ underscores the robustness of the $N = 32$ new magic number, whereas the enhanced transition strength in $^{55} Sc$ indicates the rapid erosion of the $N = 34$ shell gap with the occupancy of the proton orbital $π 1 f_{7/2}$ .
nucl-th0 citations
07
Quantum Complexity in Nuclear Scattering and Fission Dynamics
Saurabh V. Kadam🇺🇸 · Antonio Bjelčić🇺🇸 · Nicolas Schunck🇺🇸 · Kyle Wendt🇺🇸
Quantum computers promise advantages for simulating strongly correlated quantum many-body systems, like atomic nuclei, that are beyond the reach of classical computers. Realizing this potential requires understanding the quantum complexity structure of the target problem. We investigate the time-evolution of two key indicators of quantum complexity, bipartite entanglement entropy and non-local magic (non-stabilizerness), in nuclear reaction dynamics. We analyze two representative dynamical processes: scattering in a one-dimensional model of strongly interacting fermions governed by the Negele potential, and a realistic simulation of $^{240}$ Pu fission within time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. In the former case, we find that interactions dynamically generate both entanglement and non-local magic, leaving persistent signatures of quantum complexity in the outgoing states. In the latter, we observe that substantial quantum complexity survives in the spatial bipartition of daughter fragments well beyond scission. The presence of significant non-local magic and entanglement in both cases strongly indicate that quantum computers would provide substantial advantages for accurately simulating nuclear reaction dynamics.
↳ quant-phnucl-th0 citations
08
CGC-py: A Monte Carlo Event Generator for Gluon Saturation Physics
Haowu Duan🇨🇳 · Cong Yi🇨🇳 · Si-Wei Dai🇨🇳 · Shu-Yi Wei🇨🇳 · Wenbin Zhao🇨🇳 · Liang Zheng🇨🇳
We develop CGC-py, a Monte Carlo event generator for deep-inelastic scattering. It couples the full Color Glass Condensate (CGC) cross section for $γ^{*} p (A) \to q q ˉ + X$ to a Parton-Branching transverse-momentum-dependent backward initial-state shower, while \textsc{Pythia}~8 handles final-state radiation and hadronization. CGC-py retains the complete target-elastic and target-inelastic contributions without taking the back-to-back correlation limit, allowing single- and di-hadron observables to be generated consistently from the same event sample. We validate the generator through an analytic closure test of the single-inclusive quark spectrum and a comparison of charged-hadron spectra in $e p$ collisions with H1 data, finding excellent agreement. The predicted nuclear modification factor $R_{e Au}^{h}$ shows the expected saturation pattern: suppression at low $p_{T}^{*}$ followed by a rise toward unity at higher $p_{T}^{*}$ . A comparison with a \textsc{Pythia}~6 baseline, together with an $x_{g}$ -rescaling study, indicates that small- $x$ CGC evolution and collinear DGLAP dynamics contribute comparably to the growth of the dihadron away-side width with energy. Genuine saturation-driven broadening emerges only at the highest energies considered. Within CGC-py, $e Au$ collisions exhibit an enhanced away-side width and a suppressed back-to-back yield relative to $e p$ collisions. These nuclear effects remain modest over EIC kinematics, motivating measurements at the most forward accessible kinematics and the use of complementary observables to maximize sensitivity to gluon saturation.
↳ hep-phhep-exnucl-exnucl-th0 citations
09
Ultra-compact twin stars with hybrid equations of state from bosonic dark matter
Ishfaq Ahmad Rather🇩🇪 · Sarah Louisa Pitz🇩🇪 · Jürgen Schaffner-Bielich🇩🇪
The properties of compact stars with a strong first-order phase transition to quark matter and with an additional fluid of self-interacting bosonic dark matter (DM) are studied. We find that the inclusion of DM changes considerably the stability of mass-radius configurations relative to the naive one-fluid criterion. For compact star configurations with similar masses and different radii, so-called twin stars, the presence of DM removes the unstable segment between the hadronic and the hybrid branch, so that the stable mass-radius sequence becomes continuous after the onset of the phase transition to quark matter. We furthermore find stable ultra-compact objects (UCOs), defined by a total compactness $C = M_{tot} / R_{grav} \geq 1/3$ . We observe two distinct classes of UCOs: a DM-halo class with $f_{DM} ≳ 0.9$ , and a DM-core class at $f_{DM} ≲ 0.02$ . The two classes can be separated by the surface redshift of the normal matter, which reaches $z = 0.73$ -- $0.77$ for the DM-core class and stays below $0.45$ for the DM-halo class. Finally, we find hybrid star solutions of 'ultimate twins' with similar mass and visible radius, but different dark matter content, leading to different tidal deformabilities and surface redshifts. Future X-ray and gravitational measurements of ultra-compact neutron stars with radii and masses outside the allowed neutron star range can thereby probe the presence and the properties of DM in addition to a first-order phase transition to quark matter.
↳ astro-ph.HEhep-phnucl-th0 citations
10
TQ4Q2.0 Fragmentation Functions for Fully Heavy Tetraquark Production
Francesco Giovanni Celiberto🇪🇸
We investigate the fragmentation dynamics underlying the production of fully heavy tetraquarks by means of the TQ4Q2.0 collinear FF set, covering scalar ( $0^{++}$ ), axial-vector ( $1^{+-}$ ), and tensor ( $2^{++}$ ) configurations. The fragmentation inputs are determined within NRQCD factorization for the complete set of relevant partonic channels and are subsequently evolved across heavy-flavor thresholds through the HF-NRevo scheme. Perturbative uncertainties associated with fragmentation-scale variations are consistently propagated together with nonperturbative effects encoded in color-composite long-distance matrix elements. Attention is devoted to the axial-vector sector, whose fragmentation pattern makes it especially sensitive to intrinsic-charm contributions at LHC and FCC energies. TQ4Q2.0 therefore provides an uncertainty-aware framework for exploring fully heavy tetraquark production over a broad kinematic range and for connecting exotic-hadron spectroscopy with the partonic structure of the proton.
↳ hep-phhep-exnucl-exnucl-th0 citations
11
First Two-Hadron Form Factor from QCD
Felipe G. Ortega-Gama🇺🇸 · Raúl A. Briceño🇺🇸 · Ivan M. Burbano🇺🇸 · Robert G. Edwards🇺🇸
We present the first QCD determination of an energy-dependent form factor for a two-hadron scattering state. In particular, we calculate the QCD contribution to the forward electromagnetic $π^{+} π^{+} + γ \to π^{+} π^{+}$ amplitude at $m_{π} \approx 400$ ~MeV using lattice QCD. Because lattice calculations are performed in a finite Euclidean spacetime, where asymptotic scattering states are absent, this amplitude cannot be accessed directly from correlation functions. Instead, we can constrain this and related amplitudes nonperturbatively using a finite-volume formalism that requires two ingredients: the discrete finite-volume spectrum and finite-volume matrix elements of the electromagnetic current. We calculate three-point correlation functions coupling $π^{+} π^{+}$ finite-volume states and extract the corresponding electromagnetic matrix elements. Combining these results with the previously determined spectrum, we constrain the infinite-volume $π^{+} π^{+} + γ \to π^{+} π^{+}$ amplitude in the forward limit. Using constraints from Lorentz symmetry, unitarity, and analyticity, we describe this amplitude in terms of a single real-valued energy-dependent two-hadron form factor. The resulting amplitude and form factor agree with the Ward-Takahashi identity across all energies and moving frames considered, providing the first QCD validation of this finite-volume approach and a pathway toward first-principles studies of the electromagnetic structure and electroweak responses of resonances and multi-hadron bound states.
↳ hep-lathep-phnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE