Nuclear Theory·nucl-th

Monday·May 19, 2025

7 papers—4 primary·3 cross-listed

01
[Submitted on 15 May 2025]
Probing the refined performance of the Categorical-Boosting algorithm to the Hartree-Fock-Bogoliubov mass model with different Skyrme forces
Jin-Liang Guo · Hua-Lei Wang · Zhen-Zhen Zhang · Min-Liang Liu
Nuclear mass can offer profound insights into many physical branches, e.g., nuclear physics and astrophysics, while the predicted accuracy by nuclear mass models is usually far from satisfactory until now, especially within the fully microscopic self-consistent mean-field theory. In this project, we present the predictive power for the binding energy within the the Hartree-Fock-Bogoliubov (HFB) methods with six widely used Skyrme forces (SkM*, SkP, SLy4, SV-min, UNEDF0 and UNEDF1) and evaluate the refined performance of the machine learning based on a novel Categorical Boosting (CatBoost) algorithm to the Skyrme HFB mass models. The root-mean-square (rms) deviations between the bare HFB calculations with different Skyrme forces and the available experimental data range from the minimum, about 1.43 MeV, for the UNEDF0 parameter set to the maximum, about 7.03 MeV, for the SkM* paraterer set. For the CatBoost-refined HFB predictions, the predictive power can be significantly improved. All the prediction accurancies on the testing set can reach the level around 0.2 MeV and, meanwhile, the large model bias can be reduced. The model-repair coefficients for the adopted Skyrme parameter sets are uniformly more than 80\%. Moreover, for 21 newly measured nuclei outside AME2020, the predicted masses by the CatBoost-refined HFB models are also in good agreement with the experimental data, illustrating their good generalization abilities. Intrestingly, it is found that the optimal Skyrme parameter set that possesses the highest predictive power for the bare HFB mass calculations may be not the best candidate for the CatBoost-refined HFB model, indicating the different abilities of picking up the missing ``physics'' for different Skyrme forces by the CatBoost algorithm.
Comments:
17pages,17figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2505.10750 [pdf]
PRC(2025)·4 citations
02
[Submitted on 16 May 2025]
Collective excited states at small amplitude in neutron elastic scattering at low-energies
Do Quang Tam · Nguyen Hoang Tung · Nguyen Hoang Phuc · T. V. Nhan Hao
We investigate the contributions of isoscalar and isovector collective excitations in the neutron elastic scattering of $^{16}$ O, $^{40}$ Ca, $^{48}$ Ca, and $^{208}$ Pb nuclei by using a microscopic optical potential (MOP) derived from nuclear structure models based on self-consistent mean-field approaches. Particular attention is given to the role of these collective modes in shaping the imaginary part of the MOP and the resulting angular distributions. Our analysis indicates that both isoscalar and isovector contributions are significant for all considered targets, especially for light and medium targets. Furthermore, the Coulomb interaction is found to play an important role in describing absorption mechanisms and reproducing the experimental angular distributions.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2505.10971 [pdf]
IJMPE(2026)·0 citations
03
[Submitted on 16 May 2025]
Systematic analysis of double Gamow-Teller sum rules
Hong-Jin Xie · Yi Lu · Shu-Yuan Liang · Yang Lei · Calvin W. Johnson
Sum rules are important bulk properties of transition strength functions for atomic nuclei. Unlike the Ikeda sum rule for single Gamow-Teller transition, double Gamow-Teller transition sum rules rely on the details of many-body wavefunctions. We approximate the shell model ground state with nucleon-pair condensates, by projection after variation, and compute double Gamow-Teller (DGT) transition sum rules from both $β +$ and $β -$ directions. By systematic investigation of DGT sum rules of even-even nuclei in the $1 s 0 d$ , $1 p 0 f$ major shells, we quantitatively estimate the model-dependent fractions in the sum rules, and analyze the importance of double isospin-analogue state in the DGT strength function.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2505.11305 [pdf]
Symmetry(2025)·1 citation
04
[Submitted on 16 May 2025]
Neural Quantum States for Light Nuclei with Chiral Two- and Three-Body Interactions
Pengsheng Wen🇺🇸 · Alexandros Gezerlis🇨🇦 · Jeremy W. Holt🇺🇸
Finding high-quality trial wave functions for quantum Monte Carlo calculations of light nuclei requires a strong intuition for modeling the interparticle correlations as well as large computational resources for exploring the space of variational parameters. Moreover, for systems with three-body interactions, the wave function should account for many-body effects beyond simple pairwise correlations. In this work, we design neural networks that efficiently incorporate these factors to generate expressive wave function Ansätze for light nuclei using variational Monte Carlo. Our neural-network approach for $A = 3$ nuclei can capture, already at the level of variational Monte Carlo, the overwhelming majority of the ground-state energy estimated by Green's Function Monte Carlo (GFMC). It achieves a ground-state energy within $0.45%$ of the GFMC result for $^{3} H$ using the softest chiral interaction, representing a substantial improvement over standard variational Monte Carlo, which exhibits a $3.7%$ deviation. The result indicates the potential of neural networks to construct effective trial wave functions for quantum Monte Carlo calculations.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2505.11442 [pdf]
PRL(2026)·8 citations
05
[Submitted on 15 May 2025] (cross-list from hep-ph)
Distribution Functions of $Λ$ and $Σ^{0}$ Baryons
Yang Yu🇨🇳 · Peng Cheng🇨🇳 · Hui-Yu Xing🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳
Treating baryons as quark + interacting-diquark bound states, a symmetry-preserving formulation of a vector $\times$ vector contact interaction (SCI) is used to deliver an extensive, coherent set of predictions for $Λ, Σ^{0}$ baryon unpolarised and polarised distribution functions (DFs) -- valence, glue, and four-flavour separated sea -- and compare them with those of a like-structured nucleon. $Λ, Σ^{0}$ baryons are strangeness negative-one isospin partners within the SU $(3)$ -flavour baryon octet. This makes such structural comparisons significant. The study reveals impacts of diquark correlations and SU $(3)$ -flavour symmetry breaking on $Λ$ , $Σ^{0}$ structure functions, some of which are significant. For instance, were it not for the presence of axialvector diquarks in the $Σ^{0}$ at the hadron scale, the $s$ quark could carry none of the $Σ^{0}$ spin. The discussion canvasses issues that include helicity retention in hard scattering processes; the sign and size of polarised gluon DFs; and the origin and decomposition of baryon spins. Interpreted judiciously, the SCI analysis delivers an insightful explanation of baryon structure as expressed in DFs.
Comments:
24 pages, 10 figures, 6 tables. To appear in Eur. Phys. J. A
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2505.10663 [pdf]
EPJA(2025)·8 citations
06
[Submitted on 16 May 2025] (cross-list from hep-ph)
Some Aspects of Three-Quark Potentials (Part II)
Oleg Andreev🇩🇪
We continue our investigation of the effective string model for the triply heavy quark system, mimicking that in pure $S U (3)$ gauge theory. We present analytical and numerical studies of the three-quark potential for isosceles and collinear geometries. In the general case, we derive the asymptotic expression of the potential in the infrared limit. Here we also demonstrate the universality of the string tension and interpret the transition between two distinct regimes, occurring when one of the triangle's angles formed by the quarks is equal to $\frac{2}{3} π$ , as a breaking of permutational symmetry. This symmetry breaking implies the emergence of a heavy quark dressed by gluons, transforming in the two-index antisymmetric representation. Additionally, we discuss various aspects of the $Y$ - and $Δ$ -laws, diquarks, and connections to lattice QCD.
Comments:
36 pages, many figures; v2: typos corrected; v3: minor clarifications
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2505.11234 [pdf]
PRD(2025)·3 citations
07
[Submitted on 16 May 2025] (cross-list from hep-lat)
Thermal Static Potential and Pseudo-Scalar Quarkonium Spectral Functions from 2+1 Flavor Lattice QCD
Sajid Ali🇩🇪 · Dibyendu Bala🇩🇪 · Olaf Kaczmarek🇩🇪 · Pavan🇩🇪
Quarkonia, which are bound states of a heavy quark and antiquark, play a key role in probing the quark-gluon plasma (QGP). The dynamics of quarkonia in the QGP are encoded in their finite-temperature spectral functions. In this work, we estimate the quarkonium spectral functions in the pseudo-scalar channel using 2+1 flavor lattice QCD with a pion mass of $320 MeV$ , at temperatures of $220 MeV (1.2 T_{p c}), 251 MeV (1.4 T_{p c}) and 293 MeV (1.6 T_{p c})$ . Reconstructing the spectral function from the Euclidean lattice correlator is a well-known ill-posed problem, requiring additional physics-motivated input. We address this by smoothly matching contributions from different frequency regions of the spectral function, using appropriate physics valid for each region. The spectral function around $ω \sim 2 M_{q}$ is obtained using a non-perturbative complex potential, while for $ω ≫ 2 M_{q}$ it is modeled using results from vacuum perturbation theory. Since the pseudoscalar channel does not receive a transport contribution near $ω \sim 0$ , we find that the combination of these two regions already provides a good description of the relativistic lattice pseudoscalar correlator. We observe a substantial thermal width in the $η_{c} (1 S)$ state, indicating that pseudoscalar charmonium ( $η_{c}$ ) is nearing dissolution at the studied temperatures. In comparison, the $η_{b}$ ground state exhibits little change and remains well-defined.
Comments:
23 pages, 18 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2505.11313 [pdf]
PRD(2025)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE

Probing the refined performance of the Categorical-Boosting algorithm to the Hartree-Fock-Bogoliubov mass model with different Skyrme forces

Collective excited states at small amplitude in neutron elastic scattering at low-energies

Systematic analysis of double Gamow-Teller sum rules

Neural Quantum States for Light Nuclei with Chiral Two- and Three-Body Interactions

Distribution Functions of Λ and Σ0 Baryons

Some Aspects of Three-Quark Potentials (Part II)

Thermal Static Potential and Pseudo-Scalar Quarkonium Spectral Functions from 2+1 Flavor Lattice QCD

Affiliations

Distribution Functions of $Λ$ and $Σ^{0}$ Baryons