Nuclear Theory·nucl-th

Friday·July 17, 2026

15 papers—8 primary·7 cross-listed

01
Exploring the shell structure of trapped superfluid gases
G. Palkanoglou · R. Curry · S. Gandolfi
We provide quantum Monte Carlo calculations of a two-component Fermi system interacting with an attractive interaction confined in harmonic traps. We investigate the role of the interaction's scattering length and effective range and show its important role in modifying shell effects in the structure of these systems. We show that in the strongly interacting regime, where the scattering length is large, the dominant role to shell effects is due to the effective range. These conclusions are very relevant for nuclear physics, in particular for neutron-rich systems, and open the way to perform new atomic experiments that can help to explain the disappearance of shell-effects in nuclei.
nucl-thcond-mat.quant-gas0 citations
02
Bayesian Inference for Extracting Barrier Distributions from Fusion Excitation Functions
Aaron Philip · Pablo Giuliani · Kyle Godbey
Barrier distributions encode rich information about the structure and dynamics of fusing nuclei, but extracting them from experimental fusion cross sections requires an estimate of the fusion excitation function's second derivative. In this work we approach the task of extracting barrier distributions with uncertainty estimates from sparse experimental measurements as a Bayesian inference problem. We introduce a method based on AutoBNN, an interpretable Bayesian machine learning framework, to provide a robust statistical approach for analyzing fusion excitation functions. Benchmarking against Gaussian process regression on simulated excitation functions that span a wide range of realistic experimental conditions, we find that AutoBNN more faithfully recovers the underlying barrier distribution and reports well-calibrated uncertainties. We then apply the AutoBNN method to four experimentally measured heavy-ion fusion reactions where it mitigates spurious above-barrier structure and constrains existing predictions. Alongside these results, we have developed a user-friendly software implementation of our method, facilitating its application to future heavy and light-ion fusion experiments.
nucl-thnucl-ex0 citations
03
Impact of tensor-rank components of chiral three-nucleon forces on the single-particle structure of calcium isotopes
Tokuro Fukui · Giovanni De Gregorio · Angela Gargano · Chi Zhang · Furong Xu
Background: Chiral three-nucleon forces (3NFs) play a key role in the microscopic description of nuclear shell evolution. A recent work introduced an irreducible tensor decomposition of the chiral 3NF at next-to-next-to-leading order and showed that, in $p$ -shell nuclei, the enhancement of the $0 p_{3/2}$ -- $0 p_{1/2}$ spin--orbit (SO) splitting is mainly driven by its rank-1 component. Purpose: We extend the aforementioned analysis to the $0 f 1 p$ shell to investigate whether the same mechanism persists in a heavier valence space, and how the different tensor-rank components of the 3NF affect structure properties of calcium isotopes. Methods: Effective shell-model Hamiltonians for neutrons outside the doubly magic $^{40}$ Ca core are derived from chiral two-nucleon force plus 3NF. The latter is progressively included through its rank- $λ$ components ( $λ = 0, 1, 2, 3$ ), allowing us to isolate their impact on the evolution of the neutron single-particle structure. Results: The significant enhancement of the SO splittings for both $1 p$ and $0 f$ orbitals produced by the chiral 3NF is mainly induced by its rank-1 component. The rank-2 term gives a smaller contribution, while the rank-3 term is negligible. The rank-0 component, and to a lesser extent the rank-1 component, are found to play an important role in determining the spacings between orbitals with different orbital angular momenta. All modifications induced by the 3NF in the single-particle structure have a relevant impact on the shell-closure properties of $^{48}$ Ca. Conclusions: The dominance of the rank-1 two-pion-exchange component of the 3NF in explaining the enhancement of SO splitting -- previously identified in the $p$ shell -- persists in the $0 f 1 p$ shell. Observed effects of the 3NF related to the different angular-momentum dependence of the orbitals are shown to arise essentially from their rank-0 and rank-1 components.
nucl-thnucl-ex0 citations
04
Universal Properties of Near-Threshold Single-Neutron Resonances
Myungkuk Kim · Young-Ho Song · Hans-Werner Hammer · Youngman Kim · Dean Lee · Yuan-Zhuo Ma
We establish universal width predictions for near-threshold single-neutron resonances in $L > 0$ partial waves. Our results go beyond Wigner's well-known scaling behavior of cross sections near threshold. We show that the finite square-well potential exhibits discrete scale invariance at zero energy. From this fact, we derive an analytic baseline for the resonance width that depends only on geometry, angular momentum, and resonance energy, and not on internal short-distance nuclear details or radial excitation. This is a nontrivial property that is unique to the finite square-well potential and does not occur for other potentials. Application to observed p-wave and d-wave resonances demonstrates that the square-well result provides a robust baseline. We show that discrete scale invariance erases radial-node information in the sharp-boundary limit, but realistic Woods-Saxon diffuseness breaks this invariance, suppressing the reduced width by a factor sensitive to the internal radial excitation. These results provide a simple geometric benchmark for identifying when observed neutron resonances are controlled by universal threshold physics and when they exhibit systematic deviations driven by structure-dependent effects.
nucl-thnucl-ex0 citations
05
On the Bohr-Sommerfeld quantization condition and assault frequency in a semiclassical model for {\alpha} decay
Le Hoang Chien · Nguyen Tri Toan Phuc
We study the impacts of the Bohr-Sommerfeld quantization condition and the assault frequency on the {\alpha} decay half-life within the semiclassical model. The potential between the {\alpha} particle and daughter nucleus is calculated by the double-folding model using the CDM3Y3 density-dependent nucleon-nucleon interaction with a finite-range exchange term. We show that the proper implementation of the Bohr-Sommerfeld condition leads to a considerable change of the calculated {\alpha} decay half-life with certain forms of potential. We also propose an alternative treatment for the assault frequency based on the generalized oscillator potential. This description of assault frequency considerably improves the agreement between the calculated {\alpha} decay half-lives and the experimental data.
nucl-thNPA(2022)·5 citations
06
Toponium Spectrum in the Complex-Energy Plane
Zhanduo Tang🇺🇸 · Oliver Fast🇺🇸 · Ralf Rapp🇺🇸
The electroweak decay width of the top quark of ~2 GeV is comparable to binding energies expected for the toponium system, raising the long-standing question of whether top and antitop quarks can sustain meaningful bound states. This issue has been been reignited by recent discoveries of a cross section enhancement near the t-tbar threshold by the CMS and ATLAS collaborations in pp collisions at the LHC. Here, we deploy a T-matrix approach with an underlying Cornell potential to study the properties of the toponium system by varying the top-quark widths in the intermediate propagators. In particular, we carry out a complex-energy analysis of the T-matrix to assess how its poles, as a rigorous criterion for bound-state formation, develop from the limit of small widths to realistic ones. We also revisit the impact of the confining force in the potential on the toponium T-matrix.
nucl-th0 citations
07
Responses of multiparticle observables to multidimensional nuclear deformation in relativistic heavy-ion collisions
Ying Shan Zhao🇨🇳 · Yifeng Sun🇨🇳
Relativistic heavy-ion collisions provide a unique opportunity to probe ground-state nuclear structure through its imprint on the initial collision geometry. We investigate how multiparticle observables respond to combined variations of quadrupole deformation, triaxiality, and hexadecapole deformation, using $^{129}$ Xe+ $^{129}$ Xe collisions as a representative testing ground. We perform a joint analysis in the three-dimensional $(β_{2}, γ, β_{4})$ parameter space and construct initial-state estimators for several flow and mean transverse momentum correlation observables. At the initial-state level, $ρ_{2}$ is primarily sensitive to $β_{2}$ and $γ$ , with its sensitivity to $γ$ enhanced at nonzero $β_{2}$ . The nonlinear response coefficient $χ_{4, 22}$ is predominantly sensitive to $β_{4}$ , while its dependence on $β_{2}$ and $γ$ remains comparatively weak. Higher-order correlators exhibit more complex multidimensional response patterns; in particular, $ρ_{224}$ shows a dependence on $γ$ and $β_{4}$ that becomes more pronounced at finite $β_{2}$ . We further employ the iEBE-VISHNU hybrid model to examine whether these deformation sensitivities survive the subsequent dynamical evolution. The final-state calculations indicate that the sensitivity of $ρ_{2}$ to $β_{2}$ and $γ$ is largely preserved, whereas the $β_{4}$ sensitivity of $χ_{4, 22}$ is substantially reduced. For the other higher-order observables, the initial-state sensitivities are modified by the evolution or cannot be resolved with the present statistics.
nucl-th0 citations
08
Extracting nuclear charge radii from binding energies: a single-parameter empirical formula with structural corrections
Pengfei Ma · Minghui Hu · Kai Ren · Junlong Tian · Cheng Li
Nuclear binding energies and charge radii stem from the same underlying physics: saturation, isospin dependence, shell structure, and deformation. Binding-energy data therefore provide a natural constraint for charge-radius modeling. We propose a one-parameter charge-radius formula ( $BECR_{1p}$ ) that combines binding-energy correlations with local structural corrections. On a curated set of 893 experimental charge radii, the macroscopic BECR term alone reproduces the leading charge-radius scale with a root-mean-square deviation (RMSD) of 0.0345 fm; adding shell, odd--even, finite-size, and deformation corrections further reduces the RMSD of BECR1p to 0.0138 fm. An anisotropic kernel ridge regression (AKRR) applied to the residuals further lowers the leave-one-out cross-validation RMSD to about 0.0081 fm. We use the formula to predict charge radii for 11205 nuclei across the nuclear chart.
nucl-th1 citation
09
Production Effects and Final-state Interactions in $π_{1} \to 3 π$
D. Winney🇲🇽 · S. Gonzàlez-Solís🇪🇸 · M. Mikhasenko🇩🇪 · Ł. Bibrzycki🇵🇱 · C. Fernández-Ramírez🇪🇸 · V. Mathieu🇪🇸 · G. Montaña🇪🇸 · A. Pilloni🇮🇹 · L. Qiu🇺🇸 · A. Rodas🇺🇸 · A. P. Szczepaniak🇺🇸
We investigate the $π_{1} (1600)$ signal channel of $3 π$ in the $J^{P C} = 1^{-+} [π π]_{1^{--}} π P$ -wave. This channel has recently been analyzed by the COMPASS collaboration using the ``freed-isobar" technique which provides direct experimental access to the lineshape modifications of the $P$ -wave $π π$ sub-channel arising from both final state interactions and production processes such as the Deck mechanism. We motivate a unified formalism combining production effects and final state interactions using the Khuri-Treiman formalism, which is consistent with low-energy unitarity, analyticity, and crossing symmetry, seeded by an initial production amplitude. We demonstrate that the precise lineshape of the $π π$ mass spectrum can be used to determine the relative strength and complex phase of different production mechanisms contributing to the $3 π$ final state. We conduct a global fit of the $π_{1}$ freed-isobar data set, yielding a multi-dimensional parameterization of the $π_{1} \to 3 π$ decay amplitude at COMPASS as a function of both decay and production variables. We identify the contributions from short-range production and the Deck mechanism and extract the total $3 π$ invariant mass dependence which will be important for a future extraction of the $π_{1}$ pole position in the $ρ π$ channel.
↳ hep-phhep-exnucl-th0 citations
10
Exotic states with charm and/or strangeness
A. Martínez Torres🇧🇷 · Breno Agatão🇧🇷 · Pedro Brandão🇧🇷 · K. P. Khemchandani🇧🇷 · Luciano M. Abreu🇧🇷 · E. Oset🇪🇸
In this talk, I will discuss the properties of several exotic states with charm and/or strangeness. These states can be interpreted either as being generated from two- or three-hadron dynamics. In particular, I will focus on $D_{1} (2420)$ and some predictions of three-body states obtained from $n\bar
↳ hep-phnucl-th0 citations
11
A self-consistent Higgs-portal framework for dark matter--admixed neutron stars: Collider-motivated benchmarks meet multimessenger constraints
Adamu Issifu🇵🇹
We investigate dark matter (DM)-admixed neutron stars (NSs) within a self-consistent single-fluid relativistic mean-field framework by extending the Higgs-portal model with a massive $Z^{'}$ vector mediator. The resulting density-dependent repulsive interaction dynamically couples the baryonic matter (BM) and DM sectors, allowing the DM content to be characterized by the global particle fraction, $F_{χ} = N_{χ} / N_{B}$ , with the local DM density determined self-consistently as $n_{χ} = F_{χ} n_{B}$ , thereby eliminating the need for the externally prescribed DM Fermi momentum adopted in previous single-fluid models. Using the NL3 $ω ρ$ , DD2, and FSU2R EOSs, we show that increasing $F_{χ}$ systematically softens the nuclear equation of state (EOS), reduces the maximum NS mass by up to $\sim 29%$ , increases stellar compactness, and modifies the thermodynamic response of dense matter. We further derive exact analytical expressions for the adiabatic speed of sound, its density derivative, and the adiabatic index, providing a rigorous benchmark for assessing the causality and thermodynamic stability of DM-admixed EOSs. At the microscopic level, the BM--DM interaction is shown to be dominated by the repulsive $Z^{'}$ vector channel. Our framework establishes a direct connection between collider-motivated WIMP models and the multimessenger phenomenology of NSs, with potential implications for future gravitational-wave and X-ray observations.
↳ astro-ph.HEhep-phhep-thnucl-th0 citations
12
Relativistic corrections and high-energy resummation for exclusive heavy quarkonium photoproduction
Maxim Nefedov🇮🇱
The $O (v^{2})$ correction to the high-energy resummed coefficient function for the exclusive photoproduction of vector ( $1^{--}$ ) heavy quarkonia off hadrons is computed, thereby taking into account corrections of $O (v^{2} α_{s}^{n} ln^{n - 1} (x / ξ))$ . When expressed in terms of the physical vector-meson mass ( $M_{V}$ ) and the relative heavy-quark velocity ( $⟨ v^{2} ⟩$ ) using the Gremm-Kapustin relation, the computed correction turns out to be negligible at the scale $μ_{F} = M_{V}$ . However, it partially cancels the $μ_{F}$ dependence of the $O (v^{2})$ correction to the LO coefficient function in $α_{s}$ , thereby improving the robustness of the predictions.
↳ hep-phhep-exnucl-exnucl-th0 citations
13
Radiative corrections in neutral-current (anti)neutrino elastic scattering at $GeV$ energies I: Nucleon targets
Yi Chen🇨🇳 · Oleksandr Tomalak🇨🇳 · Bing-Song Zou🇨🇳
We introduce radiative corrections in neutral-current (anti)neutrino-nucleon elastic scattering at $GeV$ energies within the effective field theory framework. We factorize cross sections into soft and hard functions, clarify the (anti)neutrino flavor dependence at both amplitude and cross-section levels, and improve the quantum chromodynamics (QCD) contributions to low-energy neutral-current processes. The radiative corrections at the single-nucleon level reach a magnitude comparable to the contributions from strange quarks. We also compare our results with the experimental data from BNL E734 and MiniBooNE collaborations, finding excellent agreements with the experimental data.
↳ hep-phhep-exhep-latnucl-ex+10 citations
14
Investigation of hadronic effects on resonance productions in small collision systems using the EPOS4 model
Hyunji Lim🇰🇷 · Bong-Hwi Lim🇯🇵 · Minjung Kim🇨🇭 · Sanghoon Lim🇰🇷
Recent experimental results in high-multiplicity proton-proton (pp) collisions have suggested the possible emergence of collective behavior and medium-like effects previously considered characteristic of heavy-ion collisions. Resonance production provides a sensitive probe of such effects, as resonance yields and transverse-momentum distributions can be modified by hadronic interactions occurring between chemical and kinetic freeze-out. In this study, these effects are investigated using the EPOS4 event generator, in which hadronic final-state interactions are modeled through the UrQMD transport approach. By comparing calculations performed with and without UrQMD, the impact of hadronic interactions on resonance production is evaluated. In addition, the UrQMD contributions are separated into regeneration and rescattering, enabling a detailed investigation of both resonance production enhancement and the loss of reconstructible resonance signals. The analysis is performed for various mesonic and baryonic resonances with different lifetimes in pp collisions at LHC energies and is extended to p-O, O-O, and Pb-Pb collisions to study the system-size dependence of hadronic-phase effects. The results show that resonance production is governed by the competition between regeneration and rescattering, whose relative importance depends strongly on the resonance species, transverse momentum, and collision system. While rescattering suppresses reconstructible short-lived resonance signals, regeneration can significantly enhance the yields of several resonance species, particularly baryonic resonances. These findings demonstrate that hadronic interactions can play an important role even in small collision systems and highlight the need to measure resonances with different lifetimes and quantum numbers to constrain the dynamics and lifetime of the hadronic phase across collision systems.
↳ nucl-exnucl-th0 citations
15
Next-to-next-to-leading order QCD corrections to pion (kaon)-induced exclusive Drell-Yan process
Yu Jia🇨🇳 · Bernard Pire🇫🇷 · Qin-Tao Song🇨🇳 · Guang Tang🇨🇳 · Zhe-Yu Wang🇨🇳
The high-energy pion and kaon beams proposed for future experiments at J-PARC offer a unique opportunity to investigate exclusive Drell-Yan processes induced by pions or kaons, which correspond to inverse deeply virtual meson production with $M = π, K$ . To facilitate precise comparisons between theoretical predictions and forthcoming experimental data, we calculate the next-to-next-to-leading order (NNLO) QCD corrections to the processes $π^{-} p \to γ^{*} (\to l^{+} l^{-}) + n$ and $K^{-} p \to γ^{*} (\to l^{+} l^{-}) + Λ$ . Our calculations are performed within the generalized parton distribution (GPD) factorization framework, accurate to leading twist in the generalized Bjorken limit ( $Q^{2} ≫ ∣ t ∣, Λ_{QCD}^{2}$ ). We find that the NNLO QCD corrections are substantial and positive; therefore, their inclusion is imperative for reliable theoretical predictions in confrontation with future experiments.
↳ hep-phhep-exhep-latnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE