Nuclear Theory·nucl-th

Thursday·June 26, 2025

8 papers—5 primary·3 cross-listed

01
[Submitted on 25 Jun 2025]
Structure of odd-A Ag isotopes studied via algebraic approaches
Stanimir Kisyov · Stefan Lalkovski
The structure of the odd- $A$ silver isotopes $^{103 - 115}$ Ag is discussed within the frame of the Interacting boson-fermion model (IBFM). An overview of their key properties is presented, with particular attention paid to the $"$ J-1 anomaly $"$ , represented by an abnormal ordering of the lowest 7/2 $^{+}$ and 9/2 $^{+}$ states. By examining previously published data and newly performed calculations, it is demonstrated that the experimentally known level schemes and electromagnetic properties of $^{103 - 115}$ Ag can be reproduced well within IBFM-1 by using a consistent set of model parameters. The contribution of different single-particle orbitals to the structure of the lowest-lying excited nuclear states in $^{103 - 115}$ Ag is discussed. Given that the $J$ -1 anomaly brings down the 7/2 $^{+}$ level from the $j^{- 3}$ multiplet to energies which can be thermally populated in hot stellar environments, the importance of low-lying excited states in odd- $A$ silver isotopes for astrophysical processes is outlined.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2506.20144 [pdf]
Symmetry(2025)·1 citation
02
[Submitted on 25 Jun 2025]
Resonant Structures in $p^{7} Be$ Scattering and Their Connection to the Astrophysical $S$ -Factor
Anil Khachi
In this paper, we employ the Variable Phase Approach (VPA) to obtain the scattering phase shifts $ \delta(E, r) $, amplitude function $ A(r) $, and radial wavefunction $ u(r) $ for various channels involved in the astrophysical reaction $ {}^7\mathrm{Be}(p,\gamma)^8\mathrm{B} $. Using the extracted phase shifts, we compute the total and partial cross sections. It is observed that the peaks in the partial cross section correspond to resonant states in the compound nucleus, which also manifest as enhancements in the astrophysical S-factor. These resonances significantly increase the reaction probability at certain energies, particularly in the low-energy regime relevant to stellar nucleosynthesis. The VPA thus serves as a reliable and efficient method for calculating scattering phase shifts and, in turn, extracting the resonance energies of different partial waves. These resonance energies can provide valuable insight into the energy region where the astrophysical \textit{S}-factor is likely to peak.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2506.20349 [pdf]
0 citations
03
[Submitted on 25 Jun 2025]
Shell effects in nuclear charge radii based on Skyrme density functionals
Rong An · Shuai Sun · Xiang Jiang · Na Tang · Li-Gang Cao · Feng-Shou Zhang
A unified description of the charge radii throughout the entire nuclide chart plays an essential role for our understanding of nuclear structure and fundamental nuclear interactions. In this work, the influence of new term, which catches the spirit of neutron and proton pairs condensation around Fermi surface, on the charge radii has been investigated based on the Skyrme density functionals with the effective forces SLy5 and SkM $^{*}$ . The differential charge radii of even-even Ca, Ni, Sn, and Pb isotopes are employed to evaluate the validity of this theoretical model. Meanwhile, the results obtained by the relativistic density functional with the effective Lagrangian NL3 are also shown for the quantitative comparison. The calculated results suggest that the modified model can improve the trend of changes of the differential charge radii along Ca, Ni, Sn, and Pb isotopic chains, especially the shell closure effect at the neutron numbers $N = 28$ , 82 and 126. The shell quenching phenomena of charge radii can also be predicted at the neutron number $N = 50$ along the corresponding Ni and Sn isotopes, respectively. The inverted parabolic-like shapes between the two fully filled shells can also be observed, but the amplitude is gradually weakened from Ca to Pb isotopic chains. Combining the existing literatures, it suggests that the discontinuous behavior in nuclear charge radii can be described well by considering the influence of neutron Cooper pairs condensation around Fermi surface.
Comments:
29 pages, 4 figures, 1 table, To be appeared in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2506.20414 [pdf]
PRC(2025)·3 citations
04
[Submitted on 25 Jun 2025]
Framework for phase transitions between the Maxwell and Gibbs constructions at finite temperature
Constantinos Constantinou🇮🇹 · Mirco Guerrini🇮🇹 · Tianqi Zhao🇺🇸 · Sophia Han🇺🇸 · Madappa Prakash🇺🇸
The characteristics of the hadron-to-quark first-order phase transition differ depending on whether charge neutrality is locally or globally fulfilled. In $β$ -equilibrated matter, these two possibilities correspond to the Maxwell and Gibbs constructions. Recently, we presented a new framework in which a continuously-varying parameter allows one to describe a first-order phase transition in intermediate scenarios to the two extremes of fully local and fully global charge neutrality. In this work, we extend the previous framework to finite temperatures and out-of- $β$ equilibrium conditions, making it available for simulations of core-collapse supernovae and binary neutron star mergers. We investigate its impact on key thermodynamic quantities across a range of baryon densities, temperatures, and electron fractions. We find that when matter is not in $β$ -equilibrium, the pressure in the mixed phase is not constant even for the case of fully-local charge neutrality. Moreover, we compute the thermal index using three different approaches, demonstrating that the finite-temperature extension of an equation of state using a constant thermal index can be ill-defined when applied to the mixed phase.
Comments:
20 pages, 12 figures, Accepted by Physical Review D
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2506.20418 [pdf]
PRD(2025)·7 citations
05
[Submitted on 25 Jun 2025]
The nucleardatapy toolkit for simple access to experimental nuclear data, astrophysical observations, and theoretical predictions
Jérôme Margueron🇺🇸 · Christian Drischler🇺🇸 · Mariana Dutra🇧🇷 · Stefano Gandolfi🇺🇸 · Alexandros Gezerlis🇨🇦 · Guilherme Grams🇩🇪 · Sébastien Guillot🇫🇷 · Rohit Kumar🇺🇸 · Sudhanva Lalit🇺🇸 · Odilon Lourenço🇧🇷 · Rahul Somasundaram🇺🇸 · Ingo Tews🇺🇸 · Isaac Vidaña🇮🇹
Systematic comparisons across theoretical predictions for the properties of dense matter, nuclear physics data, and astrophysical observations (also called meta-analyses) are performed. Existing predictions for symmetric nuclear and neutron matter properties are considered, and they are shown in this paper as an illustration of the present knowledge. Asymmetric matter is constructed assuming the isospin asymmetry quadratic approximation. It is employed to predict the pressure at twice saturation energy-density based only on nuclear-physics constraints, and we find it compatible with the one from the gravitational-wave community. To make our meta-analysis transparent, updated in the future, and to publicly share our results, the Python toolkit \texttt{nucleardatapy} is described and released here. Hence, this paper accompanies \texttt{nucleardatapy}, which simplifies access to nuclear-physics data, including theoretical calculations, experimental measurements, and astrophysical observations. This Python toolkit is designed to easily provide data for: i) predictions for uniform matter (from microscopic or phenomenological approaches); ii) correlation among nuclear properties induced by experimental and theoretical constraints; iii) measurements for finite nuclei (nuclear chart, charge radii, neutron skins or nuclear incompressibilities, etc.) and hypernuclei (single particle energies); and iv) astrophysical observations. This toolkit provides data in a unified format for easy comparison and provides new meta-analysis tools. It will be continuously developed, and we expect contributions from the community in our endeavor.
Comments:
72 pages, 59 figures, nucleardatapy toolkit (Python)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2506.20434 [pdf]
EPJA(2026)·8 citations
06
[Submitted on 25 Jun 2025] (cross-list from hep-th)
Comparison between Causal and Acausal Diffusion: a Schwinger-Keldysh Effective Field Theory Perspective
Navid Abbasi🇨🇳 · Matthias Kaminski🇺🇸 · Dirk H. Rischke🇩🇪
In Fick's time-honored theory of diffusion, the system responds instantaneously to external perturbations, resulting in acausal behavior. Maxwell-Cattaneo theory addresses this issue by introducing a relaxation time, rendering the diffusion process causal. We focus on systems where this relaxation time is comparable to the diffusion time and significantly larger than the relaxation times of all other non-conserved operators. In such systems, late-time diffusion is influenced by this relaxation process, leading to a theory of quasi-diffusion. Using the Schwinger-Keldysh Effective Field Theory (SK-EFT) framework, we compare the theories of diffusion and quasi-diffusion by analyzing the real-time dynamics of correlation functions both in linear response and at one-loop order. In particular, we show that the one-loop corrections in the causal (quasi-diffusion) theory, in both the underdamped and the overdamped cases, are governed by two universal functions. In the overdamped case, the behavior mirrors that of the acausal (diffusion) theory, which has recently been applied for precision tests of SK-EFT in diffusive systems. We suggest that our results in the underdamped limit can also be used for precision tests in quasi-diffusive systems.
Comments:
31 pages, 12 figures, 1 table
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2506.20500 [pdf]
JHEP(2026)·8 citations
07
[Submitted on 25 Jun 2025] (cross-list from hep-th)
Reflection positivity in Euclidean formulations of relativistic quantum mechanics of particles
Gohin Shaikh Samad · W.N.Polyzou
This paper discusses the general structure of reflection positive Euclidean covariant distributions that can be used to construct Euclidean representations of relativistic quantum mechanical models of systems of a finite number of degrees of freedom. Because quantum systems of a finite number of degrees of freedom are not local, reflection positivity is not as restrictive as it is in a local field theory. The motivation for the Euclidean approach is that it is straightforward to construct exactly Poincaré invariant quantum models of finite number of degrees of freedom systems that satisfy cluster properties and a spectral condition. In addition the quantum mechanical inner product can be computed without requiring an analytic continuation. Whether these distributions can be generated by a dynamical principle remains to be determined, but understanding the general structure of the Euclidean covariant distributions is an important first step.
Comments:
22 pages
Subjects:
High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2506.20526 [pdf]
0 citations
08
[Submitted on 25 Jun 2025] (cross-list from hep-ph)
DeepQuark: A Deep-Neural-Network Approach to Multiquark Bound States
Wei-Lin Wu🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
For the first time, we implement the deep-neural-network-based variational Monte Carlo approach for the multiquark bound states, whose complexity surpasses that of electron or nucleon systems due to strong SU(3) color interactions. We design a novel and high-efficiency architecture, DeepQuark, to address the unique challenges in multiquark systems such as stronger correlations, extra discrete quantum numbers, and intractable confinement interaction. Our method demonstrates competitive performance with state-of-the-art approaches, including diffusion Monte Carlo and Gaussian expansion method, in the nucleon, doubly heavy tetraquark, and fully heavy tetraquark systems. Notably, it outperforms existing calculations for pentaquarks, exemplified by the triply heavy pentaquark. For the nucleon, we successfully incorporate three-body flux-tube confinement interactions without additional computational costs. In tetraquark systems, we consistently describe hadronic molecule $T_{cc}$ and compact tetraquark $T_{bb}$ with an unbiased form of wave function ansatz. In the pentaquark sector, we obtain weakly bound $D ˉ^{*} Ξ_{cc}^{*}$ molecule $P_{cc c ˉ} (5715)$ with $S = \frac{5}{2}$ and its bottom partner $P_{bb b ˉ} (15569)$ . They can be viewed as the analogs of the molecular $T_{cc}$ . We recommend experimental search of $P_{cc c ˉ} (5715)$ in the D-wave $J / ψ Λ_{c}$ channel. DeepQuark holds great promise for extension to larger multiquark systems, overcoming the computational barriers in conventional methods. It also serves as a powerful framework for exploring confining mechanism beyond two-body interactions in multiquark states, which may offer valuable insights into nonperturbative QCD and general many-body physics.
Comments:
17 pages, 7 figures, 9 tables. Version published in PRL
Subjects:
High Energy Physics — Phenomenology (hep-ph); cs.AI (cs.AI); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2506.20555 [pdf]
PRL(2026)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE