Nuclear Theory·nucl-th

Tuesday·December 24, 2024

16 papers—7 primary·9 cross-listed

01
[Submitted on 20 Dec 2024]
B(E2) strength in $^{36, 38}$ Ca and in mirror nuclei 36S, 38Ar
Jacek Okolowicz🇵🇱 · Marek Ploszajczak🇫🇷
Recently, $B (E 2, 0_{1}^{+} \to 2_{1}^{+})$ transition strength have been measured in $^{36}$ Ca and $^{38}$ Ca. Surprisingly, the measured value in $^{36}$ Ca: $B (E 2 ↑) = 131 (20)$ e $^{2}$ fm $^{4}$ , is significantly larger than in $^{38}$ Ca, where $B (E 2 ↑) = 101 (11)$ e $^{2}$ fm $^{4}$ , whereas an opposite tendency of $B (E 2)$ values is seen in the mirror nuclei $^{36}$ S and $^{38}$ Ar. The resonance $2_{1}^{+}$ in $^{36}$ Ca lies 465 keV above the proton emission threshold and its description requires inclusion of the coupling to the continuum. In this work, we are analyzing $B (E 2 ↑)$ values in $^{36}$ Ca, $^{36}$ S, $^{38}$ Ca, and $^{38}$ Ar using the real-energy continuum shell model, the so-called shell model embedded in the continuum, in the $(1 s_{1/2} 0 d_{3/2} 0 f_{7/2} 1 p_{3/2})$ model space with the monopole adjusted effective interaction ZBM-IO.
Comments:
12 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2412.16362 [pdf]
Acta Phys.Polon.Supp.(2025)·1 citation
02
[Submitted on 21 Dec 2024]
Nuclear structure properties of $^{193 - 200}$ Hg isotopes within large-scale shell model calculations
Subhrajit Sahoo · Praveen C. Srivastava · Noritaka Shimizu · Yutaka Utsuno
Large-scale shell-model calculations have been performed to study the nuclear structure properties of Hg isotopes with mass varying from $A = 193$ to $A = 200$ . The shell-model calculations are carried out in the 50 $\leq Z \leq$ 82 and 82 $\leq N \leq$ 126 model space using monopole-based truncation. We present detailed studies on low-energy excitation spectra, energy systematics, and collective properties of Hg isotopes, such as reduced transition probabilities, quadrupole, and magnetic moments along the isotopic chain. The evolution of wave function configurations with spin is analyzed in the case of even- $A$ Hg isotopes. The shell-model results are in reasonable agreement with the experimental data and predictions are made where experimental data are unavailable. The shapes of Hg isotopes are also investigated through the energy-surface plots.
Comments:
18 pages, 18 figures and 4 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2412.16518 [pdf]
PRC(2024)·6 citations
03
[Submitted on 21 Dec 2024]
Reaction mechanism of quasi-free knockout processes in exotic RI beam era
Kazuki Yoshida · Junki Tanaka
The quasi-free nucleon knockout reaction has been revealed the single-particle nature of nuclei. Thanks to the advances in experimental techniques and reaction theory, various new aspects of nuclei are being revealed by knockout reactions. In this article, we review the basic concept of the quasi-free knockout reaction, and recent achievements in the SEASTAR project using the MINOS system. We also present our new findings on the low-energy nucleon knockout reaction and the $α$ knockout reaction. The combination of the (microscopic) structure theory, reaction theory and experiments will be the key to a complete understanding of the $α$ formation and its universality in the coming decades. Noble clusters, e.g., $d$ , $t$ , $^{3}$ He, etc. are in the scope of the ONOKORO project. The implementation of the two (and more) nucleon correlation in the reaction theory is essential to connect the properties of such clusters and the reaction observables. A new framework, CDCCIA, is introduced for this purpose, which will also be applicable to the two-nucleon knockout reactions, e.g., $(p, 3 p)$ , $(p, 2 p n)$ , and $(p, p 2 n)$ .
Comments:
Contribution to review article for the symposium "Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects", 33 pages, 13 figures, to be submitted to PTEP
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2412.16649 [pdf]
PTEP(2026)·2 citations
04
[Submitted on 22 Dec 2024]
Radiative Energy Loss in a Temperature-Evolving QGP with Dynamical Constituents
Bithika Karmakar🇨🇿 · Magdalena Djordjevic🇷🇸
We present a theoretical formalism for calculating first-order-in-opacity radiative energy loss that incorporates the spatial and temporal temperature evolution of the quark-gluon plasma (QGP) in a finite-size QCD medium with dynamical (i.e., moving) constituents. The derived expressions allow for arbitrary temperature profiles, enabling detailed evaluations of radiative energy loss across different medium-evolution scenarios. Importantly, the resulting kernel applies to both single partons (R = 0) and jets (R > 0) via an out-of-cone selection, providing a unified starting point for precision QGP tomography.
Comments:
41 pages, 12 figures: A section and a figure have been added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2412.17106 [pdf]
PRC(2026)·2 citations
05
[Submitted on 23 Dec 2024]
Effects of a first-order QCD phase transition on light nucleus production
He Liu🇨🇳 · Kai-Jia Sun🇨🇳 · Peng-Cheng Chu🇨🇳
Using an extended Polyakov-looped Nambu--Jona-Lasinio (PNJL) model to describe the baryon density fluctuations of quark matter along the isentropic trajectories corresponding to different $s / ρ_{B}$ values extracted from Au+Au collisions at energies $s_{N N} = 7.7 - 200$ GeV, we investigate the effects of the first-order phase transition on the light nucleus yield ratio $N_{t} \times N_{p} / N_{d}^{2}$ . The results indicate that the second-order scaled density moment $y_{2}$ , used to quantify density fluctuations, rapidly increases to form a peak when the isentropic trajectories pass through the phase coexistence region. We extract the yield ratios $N_{t} \times N_{p} / N_{d}^{2}$ at chemical freeze-out from the isentropic trajectories at different collision energies and found significant enhancements at 19.6 GeV and 27 GeV. This is similar to the trends observed by the STAR experiment, suggesting that the enhancements in the yield ratios $N_{t} \times N_{p} / N_{d}^{2}$ observed in the STAR experiment could be explained by the density fluctuations generated in the first-order phase transition region.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2412.17621 [pdf]
1 citation
06
[Submitted on 23 Dec 2024]
Axion effects on quark matter and quark-matter cores in massive hybrid stars
He Liu🇨🇳 · Yu-Heng Liu🇨🇳 · Yong-Hang Yang🇨🇳 · Min Ju🇨🇳 · Xu-Hao Wu🇨🇳 · Hong-Ming Liu🇨🇳 · Peng-Cheng Chu🇨🇳
Using a three-flavor Nambu--Jona-Lasinio model to describe the charge-parity violating effects through axion field, we investigate the axion effects on quark matter and quark-matter cores in massive hybrid stars. The properties of quark matter vary with the scaled axion field $a / f_{a}$ in a periodic manner, with a period of $2 π$ . Within the range from 0 to $π$ , axion field decrease the baryon chemical potential of the first-order phase transition, leading to an increase in normalized pressure and stiffening of the quark matter equation of state. The effect of axions on hybrid star matter that includes the hadron-quark phase transition is contrary to expectations. The axion field shifts the onset of the hadron-quark mixed phase to lower densities but slightly softens the equation of state of the mixed phase matter, which also results in a slight decrease in the maximum mass and corresponding radius of the hybrid stars. However, we also find that the lowering of the onset of the mixed phase significantly increases the radius and mass of the quark-matter core in the hybrid star. Therefore, our results indicate with axion effects, a sizable quark-matter core can appear in $2 M_{⊙}$ massive neutron stars.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2412.17624 [pdf]
PRD(2025)·6 citations
07
[Submitted on 23 Dec 2024]
Electromagnetic Selection Rules for $^{24} Mg$ in a $6 α$ Cluster Model with $D_{4 h}$ Symmetry
Gianluca Stellin🇫🇷 · Karl-Heinz Speidel🇩🇪
In the framework of a macroscopic $α$ -cluster model, the structural properties and the spectroscopy of the $^{24} Mg$ nucleus are investigated. Special attention is devoted to the electromagnetic selection rules imposed by the point-symmetry group $D_{4 h}$ that leaves invariant the adopted $6 α$ equilibrium configuration, a square bipyramid. The analysis entails the application of group-theoretical identities and character tables, in a way familiar to quantum chemists. The results show that the occurrence of interband E0, E2, and M1, M2, M3 transitions is strictly regulated by the transformation properties of the excited vibrational modes to which the states in the process belong. Unlike the $^{12} C$ nucleus in the $D_{3 h}$ -symmetric $3 α$ arrangement, M1 transition channels are active between states corresponding to a single quantum of vibrational excitation. Conversely, the measured E1 strengths in the $^{24} Mg$ spectrum are attributable to the excitation of single-nucleon degrees of freedom, as E1 transitions are forbidden by the model. The present investigation is a only part of a wider work, encompassing the spectrum and the whole electromagnetic properties of this nucleus in the considered $D_{4 h}$ -symmetric configuration, in preparation.
Comments:
21 pages, 10 tables, 2 figures. Submitted to the Journal of Physics G
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2412.17782 [pdf]
J.Phys.G(2026)·1 citation
08
[Submitted on 20 Dec 2024] (cross-list from hep-ph)
Dispersion relation for hadronic light-by-light scattering: $η$ and $η^{'}$ poles
Simon Holz🇨🇭 · Martin Hoferichter🇨🇭 · Bai-Long Hoid🇨🇭 · Bastian Kubis🇩🇪
The pseudoscalar-pole contributions to hadronic light-by-light scattering are determined by the respective transition form factors (TFFs) into two virtual photons. These TFFs constitute complicated functions of the photon virtualities that, in turn, can be reconstructed in a dispersive approach from their discontinuities. In this work, we present such an analysis for the $η^{(')}$ TFFs, implementing a number of constraints from both experiment and theory: normalizations from the $η^{(')} \to γ γ$ decay widths, unitarity constraints from the $η^{(')} \to π^{+} π^{-} γ$ spectra, chiral symmetry for the $η^{(')} \to 2 (π^{+} π^{-})$ amplitudes, vector-meson couplings, singly-virtual data from $e^{+} e^{-} \to e^{+} e^{-} η^{(')}$ , and the asymptotic behavior predicted by the light-cone expansion. In particular, we account for the leading left-hand-cut singularity by including effects from the $a_{2}$ resonance, necessitating the solution of an inhomogeneous Muskhelishvili-Omnès problem via a carefully chosen path deformation. The resulting TFFs allow us to evaluate the $η^{(')}$ -pole contributions to the anomalous magnetic moment of the muon, $a_{μ}^{η -pole} = 14.7 (9) \times 1 0^{- 11}$ and $a_{μ}^{η^{'} -pole} = 13.5 (7) \times 1 0^{- 11}$ , completing a dedicated program for the lowest-lying pseudoscalar intermediate states in a dispersive approach to hadronic light-by-light scattering, $a_{μ}^{PS-poles} = 91. 2_{- 2.4}^{+ 2.9} \times 1 0^{- 11}$ .
Comments:
60 pages, 20 figures, results for the space-like $η$ and $η^{'}$ transition form factors included as ancillary material, version published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2412.16281 [pdf]
JHEP(2025)·65 citations
09
[Submitted on 20 Dec 2024] (cross-list from hep-ph)
Machine Learning Neutrino-Nucleus Cross Sections
Daniel C. Hackett🇺🇸 · Joshua Isaacson🇺🇸 · Shirley Weishi Li🇺🇸 · Karla Tame-Narvaez🇺🇸 · Michael L. Wagman🇺🇸
Neutrino-nucleus scattering cross sections are critical theoretical inputs for long-baseline neutrino oscillation experiments. However, robust modeling of these cross sections remains challenging. For a simple but physically motivated toy model of the DUNE experiment, we demonstrate that an accurate neural-network model of the cross section -- leveraging only Standard-Model symmetries -- can be learned from near-detector data. We perform a neutrino oscillation analysis with simulated far-detector events, finding that oscillation analysis results enabled by our data-driven cross-section model approach the theoretical limit achievable with perfect prior knowledge of the cross section. We further quantify the effects of flux shape and detector resolution uncertainties as well as systematics from cross-section mismodeling. This proof-of-principle study highlights the potential of future neutrino near-detector datasets and data-driven cross-section models.
Comments:
24 pages, 18 figures. v3: long format, adds uncertainty quantification and ill-posedness of black-box 3d problem
Subjects:
High Energy Physics — Phenomenology (hep-ph); Machine Learning (cs.LG); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2412.16303 [pdf]
PRD(2025)·1 citation
10
[Submitted on 21 Dec 2024] (cross-list from hep-ph)
Bayesian constraints on covariant density functional equations of state of compact stars with new NICER mass-radius measurements
Jia-Jie Li🇺🇸 · Yu Tian🇺🇸 · Armen Sedrakian🇵🇱
Recent advancements in astrophysical observations of compact stars, particularly the new and updated NICER constraints, have provided mass-radius ( $M$ - $R$ ) data for pulsars spanning masses from 1 to $2 M_{⊙}$ . These data offer a unique opportunity to test modern theories of dense matter using multi-messenger constraints. Covariant density functional (CDF) models of nuclear matter, which capture a broad range of nuclear and astrophysical phenomena, provide a robust theoretical framework to interpret these observations. This study applies the Bayesian framework to a class of CDF models with density-dependent meson-nucleon couplings, specifically those based on nucleonic degrees of freedom. By incorporating the latest multi-messenger constraints, we impose tighter limits on the parameter space of these models and assess their consistency with observational data. Our analysis advances previous efforts by refining the density-dependence parameterization and integrating recent $M$ - $R$ ellipses. This enables more stringent evaluations of dense matter models in light of new astrophysical observations.
Comments:
11 pages, 4 figures and 5 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2412.16513 [pdf]
PLB(2025)·23 citations
11
[Submitted on 21 Dec 2024] (cross-list from nucl-ex)
The southern shore of the island of inversion studied via quasi-free scattering
J. Kahlbow
Neutron-rich nuclei exhibit a variety of intriguing features associated with nuclear structure evolution, deformation, and other phenomena. Particularly interesting is the region in the chart of nuclides around Z = 12 and N = 20, commonly referred to as "Island of Inversion", which is profoundly influenced by these features. Recent cutting-edge experiments performed at SAMURAI/RIBF have investigated the structure of the most neutron-rich O and F isotopes, including 27,28O and 28-30F, utilizing quasi-free scattering and invariant-mass spectroscopy techniques. This experimental campaign manifests the breakdown of the N = 20 magicity for O and F isotopes, placing them within the "Island of Inversion", as is discussed in this review article. The results are further supported by theoretical analyses employing state-of-the-art shell-model and ab-initio calculations. These nuclei serve as corner stones for the study of weak binding and continuum coupling, deformation, and halo formation. Signatures for the establishment of a superfluid regime in 28O and 29F are found. Future experimental and theoretical studies are needed to examine details.
Comments:
Contribution to review article collection for the Symposium "Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects". 25 pages, 7 figures, to be submitted to PTEP
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.16799 [pdf]
PTEP(2025)·2 citations
12
[Submitted on 22 Dec 2024] (cross-list from nucl-ex)
The Island of Inversion at $N = 40$
Martha Liliana Cortes
Our understanding of the structure of atomic nuclei largely derives from the nuclear shell model, which has proven widely successful. Further test to our interpretation of the nuclear properties is provided by the study of shell evolution. Increasing experimental information has shown that the nuclear energy shells change when going towards the most exotic nuclei, in turn making some shell closures disappear while others arise. In particular, the $N = 40$ sub-shell closure has been the subject of extensive research due to the emergence of a so-called Island of Inversion, where deformed intruder configurations dominate the wave function of the ground state. An overview of recent experimental results in the $N = 40$ Island of Inversion, particularly those performed with the combination of the MINOS hydrogen target and the DALI2 $γ$ -ray array at the RIBF are discussed.
Comments:
Contribution to review article collection for the Symposium "Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects"
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.16940 [pdf]
PTEP(2026)·4 citations
13
[Submitted on 22 Dec 2024] (cross-list from nucl-ex)
Competition of the shell closure and deformations across the doubly magic $^{78}$ Ni
Ryo Taniuchi
The properties of the neutron-rich isotope $^{78}$ Ni, long postulated to be doubly magic, have been extensively explored through recent experimental and theoretical studies. Confirmations of robust shell closures at $Z = 28$ and $N = 50$ as well as hints of competing deformations in neighboring isotopes have been obtained. Innovations of a thick liquid hydrogen target system with vertex reconstructions and the in-beam $γ$ -ray spectroscopy technique have facilitated detailed investigations into the nuclear structure of these extreme systems. Proton knockout reactions conducted at relativistic energies have provided the first experimental evidence of shape coexistence at the cornerstone nucleus $^{78}$ Ni and its vicinity. As the nuclear structure around $^{78}$ Ni influences the description of very neutron-rich systems and r-process nucleosynthesis, these findings underscore the importance of further investigations. This review encapsulates the recent results concerning the nuclear structure at the vicinity of $^{78}$ Ni on both experimental and theoretical aspects. It outlines prospective research directions that could further illuminate this complex and intriguing area of the nuclear chart.
Comments:
Contribution to review article collection for the Symposium "Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects". 23 pages, 11 figures, to be submitted to PTEP
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.16972 [pdf]
PTEP(2026)·3 citations
14
[Submitted on 23 Dec 2024] (cross-list from nucl-ex)
Deformation from zinc to zirconium
Sidong Chen · Frank Browne · Tomás R. Rodríguez · Volker Werner
Extensive gamma-ray spectroscopy of very neutron-rich nuclei of isotopes between the Ni and Sn isotopic chains was facilitated by the high luminosity LH2 target system, MINOS. Results show a persistence of deformation when going beyond the N = 60 threshold of the transition between spherical to deformed ground states at N < 60 and N > 60, respectively. Close to 78Ni, a more detailed image of the N > 50 Zn isotopes shows an erosion of the N = 50 shell closure, with core-breaking effects needed from theoretical models to replicate observation. As well as the experimental results indicating collective effects, the projected generator coordinate method is discussed in detail within the context of the neutron-rich Ge isotopes.
Comments:
Contribution to review article collection for the Symposium "Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects", 18 pages, 7 figures, to be submitted to PTEP
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.17205 [pdf]
PTEP(2026)·2 citations
15
[Submitted on 23 Dec 2024] (cross-list from hep-lat)
Spectral analysis for nucleon-pion and nucleon-pion-pion states in both parity sectors using distillation with domain-wall fermions
Andreas Hackl🇩🇪 · Christoph Lehner🇩🇪
We present a study using the distillation method to analyze the spectra of nucleon, nucleon-pion, and nucleon-pion-pion states in the positive-parity sector, as well as nucleon and nucleon-pion states in the negative-parity sector. The study uses seven domain-wall fermion ensembles with varying pion masses ( $m_{π} = 139 - 279 MeV$ ), lattice spacings ( $a^{- 1} = 1.730 GeV$ and $a^{- 1} = 2.359 GeV$ ) and volumes ( $m_{π} L = 3.8 - 7.5$ ). To address the large number of contractions in this project, we implemented an algorithm to automate the contraction of nucleon-pion correlation functions that contain an arbitrary number of pions. In the positive parity sector, we extrapolate the nucleon mass to the physical point. This study demonstrates the effectiveness of the distillation method for baryonic quantities with a focus on multi-hadronic states and establishes a foundation for future work.
Comments:
31 pages, 19 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2412.17442 [pdf]
PRD(2026)·8 citations
16
[Submitted on 23 Dec 2024] (cross-list from nucl-ex)
Shell Migration at N = 32, 34 around Ca Region
Hongna Liu · Sidong Chen · Frank Browne
The neutron numbers N = 32 and 34 are new magic numbers suggested in neutron-rich $p f$ -shell nuclei. In this article, we discuss the experimental observables and state-of-the-art theoretical calculations that characterize and explain the shell evolution leading to new magic numbers. Particular focus shall be afforded to the experimental progress of the shell migration study at and beyond N = 32, 34 in Ar, K, Ca, and Sc isotopes at the RIBF using direct reactions with liquid hydrogen targets over the past ten years. The results prove the double magicity of \ts{52,54}Ca, and support the persistence of the N = 34 subshell closure below Z = 20 with a sharp weakening beyond Z = 20. Future measurements of intruder bands of N = 32, 34 nuclei and shell evolution towards N = 40 are discussed within the context of an upgraded RIBF facility and the development of novel detection systems.
Comments:
This article is part of a review collection from the ''Symposium Direct reactions and spectroscopy with hydrogen targets: past 10 years at the RIBF and future prospects'', to be submitted to PTEP
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.17588 [pdf]
PTEP(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE