Nuclear Theory·nucl-th

Monday·November 27, 2023

21 papers—8 primary·13 cross-listed

01
[Submitted on 23 Nov 2023]
Spin dynamics in intermediate-energy heavy-ion collisions with rigorous angular momentum conservation
Rong-Jun Liu🇨🇳 · Jun Xu🇨🇳
We have revisited the spin dynamics in intermediate-energy heavy-ion collisions based on the improved spin- and isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, particularly with the constraint of rigorous angular momentum conservation incorporated. We have studied the spin polarization of free nucleons and tritons/ $^{3}$ He as well as the spin alignment of deuterons, and predicted the flow splittings for their different spin states. We have also demonstrated that the spin-dependent potential may enhance dissipations and thus have a non-negligible effect on the spin-averaged transverse flow at low collision energies. When rigorous angular momentum conservation in each spin-dependent nucleon-nucleon collision is incorporated, it affects the overall dynamics, the flow, and also the spin polarization, while the effects of the spin-orbit potential on the spin-related observables are still appreciable. The well-developed SIBUU model could be further extended to include hyperons or vector mesons, or used as a hadronic afterburner for spin-related studies in relativistic heavy-ion collisions, with more inelastic channels incorporated in the future.
Comments:
13 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
2311.13769 [pdf]
PRC(2024)·11 citations
02
[Submitted on 23 Nov 2023]
Conformable Fractional Bohr Hamiltonian with Bonatsos and Double-Well Sextic Potentials
M. M. Hammad
Using the conformable fractional calculus, a new formulation of the Bohr Hamiltonian is introduced. The conformable fractional energy spectra of free- and two- parameters anharmonic oscillator potentials are investigated. The energy eigenvalues and wave functions are calculated utilizing the finite-difference discretization method. It is proved that the conformable fractional spectra of the free-parameter Bonatsos potentials, $\frac{β ^{2 n}}{2}$ , close completely the gaps between the classical spectra of the vibrational U(5) dynamical symmetry, the $E (5) - β^{2 n}$ models, and the E(5) critical point symmetry. The ground effective sextic potential, which generates both the ground state and the $β$ excited states $0^{+}$ , is considered to have two degenerate minima. In this case, the conformable fractional spectra of sextic potentials show a change, as a function of barrier height, from $γ$ -unstable O(6) energy level sequence to the spectrum of $E (5) - β^{6}$ model and simultaneously provide new features. The shape coexistence phenomena, in the ground band states, are identified. The energy spectrum and shape coexistence with mixing phenomena in $^{96} MO$ nucleus are discussed in the framework of the conformable fractional Bohr Hamiltonian.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2311.14080 [pdf]
Phys.Scripta(2021)·9 citations
03
[Submitted on 24 Nov 2023]
Exploring percolation phase transition in the three-dimensional Ising model with machine learning
Ranran Guo🇨🇳 · Xiaobing Li🇨🇳 · Rui Wang🇨🇳 · Shiyang Chen🇬🇧 · Yuanfang Wu🇨🇳 · Zhiming Li🇨🇳
The percolation study offers valuable insights into the characteristics of phase transition, shedding light on the underlying mechanisms that govern the formation of global connectivity within the system. We explore the percolation phase transition in the 3D cubic Ising model by employing two machine learning techniques. Our results demonstrate the capability of machine learning methods in distinguishing different phases during the percolation transition. Through the finite-size scaling analysis on the output of the neural networks, the percolation temperature and a correlation length exponent in the geometrical percolation transition are extracted and compared to those in the thermal magnetization phase transition within the 3D Ising model. These findings provide a valuable way essential for enhancing our understanding of the property of the QCD critical point, which belongs to the same universality class as the 3D Ising model.
Comments:
9 pages, 6 figures, 1 table, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2311.14245 [pdf]
CPC(2025)·1 citation
04
[Submitted on 24 Nov 2023]
Nuclear level density from relativistic density functional theory and combinatorial method
Xiao-Fei Jiang · Xin-Hui Wu · Peng-Wei Zhao · Jie Meng
Nuclear level density is calculated with the combinatorial method based on the relativistic density functional theory including pairing correlations. The Strutinsky method is adopted to smooth the total state density in order to refine the prediction at low excitation energy. The impacts of pairing correlations and moments of inertia on the nuclear level density are discussed in detail. Taking $^{112} Cd$ as an example, it is demonstrated that the nuclear level density based on the relativistic density functional PC-PK1 can reproduce the experimental data at the same level as or even better than the previous approaches.
Comments:
15 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2311.14250 [pdf]
PLB(2024)·10 citations
05
[Submitted on 24 Nov 2023]
Nuclear stability and the Fold Catastrophe
Samyak Jain · A. Bhagwat
A geometrical analysis of the stability of nuclei against deformations is presented. In particular, we use Catastrophe Theory to illustrate discontinuous changes in the behavior of nuclei with respect to deformations as one moves in the N - Z space. We construct a minimalistic deformation model using the microscopic-macroscopic approach. A third-order phase transition is found in the liquid-drop model, which translates to a complete loss of stability (using the Fold catastrophe) when shell effects are included. The analysis is found to explain the instability of known fissile nuclei and also justify known decay chains of heavy nuclei.
Comments:
16 pages, 3 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Mathematical Physics (math-ph); math.MP (math.MP)
arXiv:
2311.14293 [pdf]
1 citation
06
[Submitted on 24 Nov 2023]
Universal characterization of Efimovian $D^{0} nn$ System via Faddeev Techniques
Ghanashyam Meher🇮🇳 · Sourav Mondal🇮🇳 · Udit Raha🇮🇳
We demonstrate remnant structural universality in a putative S-wave $2 n$ -halo-bound $D^{0} nn$ system in the $J = 0, T = 3/2$ channel by invoking the zero-coupling limit (ZCL), which eliminates sub-threshold decay channels. Within this framework, we evaluate the one- and two-body matter density form factors, their associated root mean-square radii, and the $n$ - $D^{0}$ - $n$ opening angle. Our analysis is carried out at leading order using a quantum mechanical Faddeev technique in the momentum representation. Employing Jacobi momenta, we construct a complete partial-wave basis to expand the full three-body $D^{0} nn$ wave function across distinct rearrangement channels. Projection onto this basis yields a coupled set of Faddeev integral equations that govern the multiple-scattering dynamics of the constituent coupled spin-isospin subsystems. By introducing short-range separable interactions and expressing the two-body scattering amplitudes via spectator functions, we establish a direct correspondence with the familiar Skornyakov-Ter-Martirosyan equations from halo-EFT approach at leading order. A regulator-dependent analysis highlights the Efimov-like character of the three-body observables, with ground state properties exhibiting marked sensitivity to cutoff variations. However, the inclusion of a three-body force suppresses this dependence, as expected from renormalization-group invariance. We thereby conclude that, for sufficiently shallow three-body binding, the $D^{0} nn$ system in the ZCL exhibits a universal halo-bound structure. The subtle implications of range-like corrections at LO are addressed at a qualitative level in this analysis.
Comments:
15 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2311.14325 [pdf]
NPA(2026)·1 citation
07
[Submitted on 24 Nov 2023]
Impact of two-body currents on magnetic dipole moments of nuclei
T. Miyagi · X. Cao · R. Seutin · S. Bacca · R. F. Garcia Ruiz · K. Hebeler · J. D. Holt · A. Schwenk
We investigate the effects of two-body currents on magnetic dipole moments of medium-mass and heavy nuclei using the valence-space in-medium similarity renormalization group with chiral effective field theory interactions and currents. Focusing on near doubly magic nuclei from oxygen to bismuth, we have found that the leading two-body currents globally improve the agreement with experimental magnetic moments. Moreover, our results show the importance of multi-shell effects for $^{41}$ Ca, which suggest that the $Z = N = 20$ gap in $^{40}$ Ca is not as robust as in $^{48}$ Ca. The increasing contribution of two-body currents in heavier systems is explained by the operator structure of the center-of-mass dependent Sachs term.
Comments:
6 pages, 4 figures, supplemental material included
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2311.14383 [pdf]
PRL(2024)·58 citations
08
[Submitted on 24 Nov 2023]
Coulomb screening in the momentum-space description of the proton-deuteron elastic scattering: Why the renormalization is needed?
A. Deltuva
Proton-deuteron elastic scattering is considered in the framework of momentum-space Faddeev equations with the screening method for the Coulomb interaction. It is shown how the interplay of the proton-proton Coulomb potential and the deuteron pole in the neutron-proton transition operator leads to coinciding singularities in the Faddeev equation. As a consequence, the renormalization of the scattering amplitude is needed in the unscreened Coulomb limit. This finding possibly explains why no need for the renormalization was conjectured in a previous work [Witała et al., Eur.~Phys.~J.~A 41, 369 (2009)] missing the coincidence of those singularities.
Comments:
7 pages, no figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2311.14605 [pdf]
PRC(2024)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE