Nuclear Theory·nucl-th

Wednesday·April 9, 2025

9 papers—6 primary·3 cross-listed

01
[Submitted on 8 Apr 2025]
Entanglement in two-quasiparticle-triaxial-rotor systems: Chirality, wobbling, and the Pauli effect
Q. B. Chen · S. Frauendorf
We investigate the entanglement in two-quasiparticle plus triaxial-rotor (PTR) model for the particle-hole configuration $π (1 h_{11/2})^{1} \otimes ν (1 h_{11/2})^{- 1}$ , the particle-particle configuration $π (1 h_{11/2})^{1} \otimes ν (1 h_{11/2})^{1}$ , and two-proton particles configuration $π (1 h_{11/2})^{2}$ for different values of the triaxiality parameter. The entanglement between the angular momenta of the two quasiparticles and the total angular momentum is quantified by the three bipartite concurrences $C$ of one type of angular momentum with the other two angular momenta and the area $F$ of the triangle formed by the bipartite concurrences. Collective chiral and wobbling modes are identified for $γ > 1 5^{\circ}$ via spin coherent state (SCS) maps and spin squeezed state (SSS) plots. Their entanglement increases from moderate values at the band head to near-maximal values at $I = 20$ . The area $F$ of the chiral partners changes order as function of $I$ which reflects the crossing of the partner bands as a signature of chirality. For the $π (1 h_{11/2})^{2}$ configuration, the antisymmetrization required by the Pauli exclusion principle causes strong entanglement between the two protons, which significantly amplifies the area $F$ . For $γ < 1 5^{\circ}$ , the lowest bands become various uniformly rotating quasiparticle configurations, which have large values of $F$ for all values $I$ .
Comments:
17 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2504.05608 [pdf]
PRC(2025)·6 citations
02
[Submitted on 8 Apr 2025]
Assessment of effect of local approximation on single folding potential at low and intermediate incident energies
K. Ishida · H. Nakada
To the single folding potentials (SFPs) for the nucleon-nucleus ( $N$ - $A$ ) elastic scatterings, local approximations (LAs) have customarily been applied. The LA discussed by Brieva and Rook has been well-known, which only needs the density profile as the structure information of the target nucleus. By applying the M3Y-P6 interaction both to the target wave functions and the real part of SFP, supplemented with the Koning-Delaroche phenomenological imaginary potential, the precision of the Brieva-Rook LA on the SFP is investigated for the proton-nucleus elastic scatterings at $ϵ_{p} = 16 - 80 MeV$ incident energies. The analyzing powers as well as the differential cross sections are in reasonable agreement with the available data. The precision of the LA for the central and LS channels is distinctly examined. Although the LA works well at small angles ( $θ_{c.m.} ≲ 3 0^{\circ}$ ), it gives rise to sizable deviation from the results of the non-local SFP (\textit{i.e.}, without the LA) at larger angles. The results of the non-local SFP are always in better agreement with the data. The LA for the LS channel influences the differential cross-sections, and the LA for the central channel does the spin observables. It is found that the precision of the LA well correlates to the momentum transfer $q$ , and the discrepancy becomes sizable at $q ≳ 1.5 fm^{- 1}$ . The LA is also examined for a halo nucleus, by taking $^{86}$ Ni as an example. The precision is slightly worse than in stable nuclei. Difference from the prediction of the empirical potential in the observables of the $p$ - $^{86}$ Ni scattering is discussed.
Comments:
19 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2504.05664 [pdf]
PRC(2025)·0 citations
03
[Submitted on 8 Apr 2025]
Possible existence of pygmy dipole resonance built on excited states in a neutron-rich $^{80}$ Ge nucleus
L. Tan Phuc · N. Dinh Dang · R. Li · N. Quang Hung
The pygmy dipole resonance (PDR) at the low-lying tail of the giant dipole resonance (GDR) is an interesting research subject as it carries important information about the nuclear surface with mixed isoscalar and isovector vibrations in $N > Z$ systems. The present paper investigates the possible existence of the PDR built on excited states in a neutron-rich $^{80}$ Ge nucleus using the phonon damping model (PDM) with and without pairing correlation at zero and finite temperatures. The results obtained within the PDM with exact pairing (EP+PDM) reveal the appearance of two enhanced $γ$ -transitions $E_{γ} = 7.25$ and 7.35 MeV at $T = 0.6$ MeV, which carry the PDR nature and hence implying the possible existence of PDR built on excited states in this nucleus. These two $γ$ -energies nicely match with a recent experimental observation, thus indicating the crucial role of the inclusion of exact pairing solution in the precise description of low-lying $γ$ -transitions. The partition function-based analysis shows that this predicted PDR at $T =$ 0.6MeV is mainly contributed by the first $2^{+}$ excited state of the $^{80}$ Ge nucleus. The isospin mixing at the nuclear surface is also observed in the investigated PDR at $T = 0.6 - 0.7$ MeV. The primary mechanism underlying the emergence of the hot PDR is found due to the coupling of GDR phonon to non-collective particle-particle and hole-hole configurations at finite temperatures within the PDM framework, along with the shift in particle-hole excitation energies due to thermal pairing correlations
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2504.05797 [pdf]
PRC(2024)·3 citations
04
[Submitted on 8 Apr 2025]
Effects of strange molecular partners of $P_{c}$ states in $γ p \to K Σ$ reactions
Jian-Cheng Suo🇨🇳 · Di Ben🇨🇳 · Bing-Song Zou🇨🇳
Our previous studies revealed evidence of the strange molecular partners of $P_{c}$ states, $N (2080) 3/ 2^{-}$ and $N (2270) 3/ 2^{-}$ , in the $γ p \to K^{*+} Σ^{0} / K^{* 0} Σ^{+}$ and $γ p \to ϕp$ reactions. Motivated by the differential cross-section data for $γ p \to K^{+} Σ^{0}$ from CLAS 2010, which exhibits some bump structures at $W \approx$ 1875, 2080 and 2270 MeV, we extend our previous analysis by investigating the effects of $N (1535) 1/ 2^{-}$ , $N (1875) 3/ 2^{-}$ , $N (2080) 1/ 2^{-} & 3/ 2^{-}$ and $N (2270) 1/ 2^{-}, 3/ 2^{-} & 5/ 2^{-}$ , as strange partners of $P_{c}$ molecular states, in the reactions $γ p \to K^{+} Σ^{0}$ and $γ p \to K^{0} Σ^{+}$ . The theoretical model employed in this study utilizes an effective Lagrangian approach in the tree-level Born approximation. It contains the contributions from $s$ -channel with exchanges of $N$ , $Δ$ , $N^{*}$ (including the hadronic molecules with hidden strangeness), and $Δ^{*}$ ; $t$ -channel; $u$ -channel; and the generalized contact term. The results based on the final fitted parameters are in good agreement with all available experimental data of both cross-sections and polarization observables for $γ p \to K^{+} Σ^{0}$ and $γ p \to K^{0} Σ^{+}$ . Notably, the $s$ -channel exchanges of molecules significantly contribute to the bump structures in cross-sections for $γ p \to K Σ$ at $W \approx$ 1900, 2080 and 2270 MeV, and show considerable coherence with contributions from $s$ -channel exchanges of general resonances to construct the overall structures of cross-sections. More abundant experiments, particularly for the reaction $γ p \to K^{0} Σ^{+}$ , are necessary to further strengthen the constraints on the theoretical models.
Comments:
28 pages, 15 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2504.05811 [pdf]
PRC(2025)·5 citations
05
[Submitted on 8 Apr 2025]
Greedy Emulators for Nuclear Two-Body Scattering
J. M. Maldonado · C. Drischler · R. J. Furnstahl · P. Mlinarić
Applications of reduced basis method emulators are increasing in low-energy nuclear physics because they enable fast and accurate sampling of high-fidelity calculations, enabling robust uncertainty quantification. In this paper, we develop, implement, and test two model-driven emulators based on (Petrov-)Galerkin projection using the prototypical test case of two-body scattering with the Minnesota potential and a more realistic local chiral potential. The high-fidelity scattering equations are solved with the matrix Numerov method, a reformulation of the popular Numerov recurrence relation for solving special second-order differential equations as a linear system of coupled equations. A novel error estimator based on reduced-space residuals is applied to an active learning approach (a greedy algorithm) to choosing training samples ("snapshots") for the emulator and contrasted with a proper orthogonal decomposition (POD) approach. Both approaches allow for computationally efficient offline-online decompositions, but the greedy approach requires much fewer snapshot calculations. These developments set the groundwork for emulating scattering observables based on chiral nucleon-nucleon and three-nucleon interactions and optical models, where computational speed-ups are necessary for Bayesian uncertainty quantification. Our emulators and error estimators are widely applicable to linear systems.
Comments:
minor changes, close to published version; 24 pages, 11 figures, and 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Data Analysis, Statistics and Probability (physics.data-an)
arXiv:
2504.06092 [pdf]
PRC(2025)·17 citations
06
[Submitted on 8 Apr 2025]
Impact of MvdW Equation of State and Neutrino Mass on r and s Process Heavy Element Nucleosynthesis in Spiral, Elliptical and Dwarf Galactic Environments and Kilonovae Events
Keith Andrew🇺🇸 · Eric Steinfelds🇺🇸 · Kristopher Andrew🇺🇸
We present an analysis of heavy element production with massive neutrinos in galaxies of varying types (spiral, elliptical, and dwarf) and kilonovae events by incorporating a Multicomponent van der Waals (MvdW) equation of state (EoS) for the opacity functions. This EoS is applied to derive opacities and calculate the yields of isotopes formed in r-process and s-process nucleosynthesis, with and without the influence of neutrino masses or oscillations. We look at both the lanthanide and actinide sequences using the MvdW parameters that involve the interaction strength and excluded volume effects. Our results reflect the characteristic differences found in r and s processes in the synthesis and long-term evolution of isotopes from the U, Th, and Sr chain across galactic environments. The inclusion of neutrino masses enhances the neutron-to-proton ratio, favoring heavier r-process isotopes and altering the overall galactic yields by cross section suppression. These findings offer insights into the interplay of nuclear physics and astrophysical environments, highlighting the sensitivity of nucleosynthetic pathways to EoS modifications and neutrino physics. We compare these results to metallicity profiles of similar models: the Galactic Leaky Box, the Galactic Inflow, and the Galactic Closed Box models and to the kilonova event GW170781.
Comments:
18 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2504.06191 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Entanglement in two-quasiparticle-triaxial-rotor systems: Chirality, wobbling, and the Pauli effect

Assessment of effect of local approximation on single folding potential at low and intermediate incident energies

Possible existence of pygmy dipole resonance built on excited states in a neutron-rich 80Ge nucleus

Effects of strange molecular partners of Pc​ states in γp→KΣ reactions

Greedy Emulators for Nuclear Two-Body Scattering

Impact of MvdW Equation of State and Neutrino Mass on r and s Process Heavy Element Nucleosynthesis in Spiral, Elliptical and Dwarf Galactic Environments and Kilonovae Events

Affiliations

Possible existence of pygmy dipole resonance built on excited states in a neutron-rich $^{80}$ Ge nucleus

Effects of strange molecular partners of $P_{c}$ states in $γ p \to K Σ$ reactions