Nuclear Theory·nucl-th

Thursday·November 14, 2024

14 papers—9 primary·5 cross-listed

01
[Submitted on 12 Nov 2024]
Triaxial nuclear shapes from simple ratios of electric-quadrupole matrix elements
Elena Atanassova Lawrie · José Nicolás Orce
Theoretical models often invoke triaxial nuclear shapes to explain elusive collective phenomena, but such assumptions are usually difficult to confirm experimentally. The only direct measurements of the nuclear axial asymmetry $γ$ is based on rotational invariants of zero-coupled products of the electric-quadrupole (E2) operator, the Kumar-Cline sum rule analysis, which generally require knowledge of a large number of E2 matrix elements connecting the state of interest. We propose an alternative assumptions-free method to determine $γ$ of even-even rotating nuclei using only two E2 matrix elements, which are among the easiest to measure. This approach is based on a simple description of nuclear rotation, where the underlying assumptions of the Davydov-Filippov model are either empirically proven or unnecessary. The $γ$ values extracted here are found in agreement with the values deduced from Kumar-Cline sum rules measurements (where available), providing further evidence that the proposed approach represents a reliable, model-independent deduction of $γ$ . The technique was applied to more than 60 deformed even-even rotating nuclei and the results indicate that rotating nuclei generally exhibit well-defined stable axially-asymmetric shapes.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2411.08130 [pdf]
Atom.Data Nucl.Data Tabl.(2025)·3 citations
02
[Submitted on 13 Nov 2024]
Investigating the possibility of extracting neutron-skin thickness in nuclei by their collisions at intermediate energies
Tian-Ze Li · Lu-Meng Liu · Jun Xu · Zhong-Zhou Ren
Inspired by various studies on extracting the density distributions of nuclei from their collisions at ultrarelativistic energies, in the present work we investigate the possibility of extracting the neutron-skin thickness $Δ r_{n p}$ in nuclei by their collisions at intermediate energies. We have analyzed the free neutron-to-proton yield ratio $n / p$ as a candidate probe at both midrapidities and forward rapidities in peripheral and central $^{124}$ Sn+ $^{124}$ Sn collisions based on an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, and found that the resulting $n / p$ yield ratio is more sensitive to the symmetry potential in the collision dynamics than to the initial $Δ r_{n p}$ in colliding nuclei in most cases. The largest effect on the $n / p$ yield ratio from the initial $Δ r_{n p}$ is observed for nucleons at large transverse or longitudinal momenta in central collisions at the collision energy of a few GeV/nucleon.
Comments:
11 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2411.08337 [pdf]
PRC(2024)·1 citation
03
[Submitted on 13 Nov 2024]
Nonautonomous Volterra Series Expansion of the Variable Phase Approximation and its Application to the Nucleon-Nucleon Inverse Scattering Problem
Gabor Balassa
In this paper, the nonlinear Volterra series expansion is extended and used to describe certain types of nonautonomous differential equations related to the inverse scattering problem in nuclear physics. The nonautonomous Volterra series expansion lets us determine a dynamic, polynomial approximation of the variable phase approximation (VPA), which is used to determine the phase shifts from nuclear potentials through first-order nonlinear differential equations. By using the first-order Volterra expansion, a robust approximation is formulated to the inverse scattering problem for weak potentials and/or high energies. The method is then extended with the help of radial basis function neural networks by applying a nonlinear transformation on the measured phase shifts to be able to model the scattering system with a linear approximation given by the first-order Volterra expansion. The method is applied to describe the 1S0 NN potentials in neutron+proton scattering below 200 MeV laboratory kinetic energies, giving physically sensible potentials and below 1% averaged relative error between the recalculated and the measured phase shifts.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.08393 [pdf]
PTEP(2024)·1 citation
04
[Submitted on 13 Nov 2024]
Bayesian evaluation of hadron-quark phase transition models through neutron star observables in light of nuclear and astrophysics data
Debanjan Guha Roy🇮🇳 · Anagh Venneti🇮🇳 · Tuhin Malik🇵🇹 · Swastik Bhattacharya🇮🇳 · Sarmistha Banik🇮🇳
We investigate the role of hybrid and nucleonic equations of state (EOSs) within neutron star (NS) interiors using Bayesian inference to evaluate their alignment with recent observational data from NICER and LIGO-Virgo (LV) collaborations. We find that smooth hybrid EOSs are slightly favoured in explaining NS mass-radius relations, particularly for pulsars such as PSR J0030+0451 and PSR J0740+6620. However, this preference is not definitive, as gravitational wave (GW) data does not significantly differentiate between our hybrid and nucleonic models. Our analysis also reveals tensions between older NICER data and recent measurements for PSR J0437-4715, highlighting the need for more flexible EOS models. Through two sampling approaches - one fixing the hadronic EOS set and the other without fixing the same, we demonstrate that the hybrid EOS model can incorporate stiffer EOSs, resulting in a better agreement with NICER data but leading to higher tidal deformability, which is less consistent with GW observations. In some recent publications a parameter $d_{c}$ , related to the trace anomaly and its derivative, is used to indicate the presence of deconfined quark matter. We find that our hadronic model, which does not include phase transition to deconfined matter, under the influence of imposed constraints, is able to predict values below 0.2 for $d_{c}$ at around five times saturation density. The hybrid model goes below this threshold at lower densities under the same conditions.
Comments:
16 pages, including Supplementary Material. Accepted in Physics Letters B
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2411.08440 [pdf]
PLB(2024)·14 citations
05
[Submitted on 13 Nov 2024]
Higher partial waves in femtoscopy
Koichi Murase🇯🇵 · Tetsuo Hyodo🇯🇵
Femtoscopy is recently gaining more attention as a new approach complementary to scattering experiments for constraining hadron-hadron interactions. We discuss the effect of higher partial waves on the two-particle correlation function, which has been neglected in traditional formulae used in the femtoscopy analyses. We consider the partial-wave expansion of the wave function in the Koonin-Pratt formula to give the correction to the correlation function by a sum of the contributions from each partial wave. We also generalize the Lednicky-Lyuboshitz formula, which was originally derived for the s-wave interaction, for higher partial waves. We find a compact representation of the generalized Lednicky-Lyuboshitz formula given by the backward scattering amplitude $f (θ = π)$ and the Fourier-Laplace transform of the relative source function, which gives an insight into the structure of the Lednicky-Lyuboshitz formula and its relation to the optical theorem. We numerically demonstrate the significance of higher partial waves with resonances using the square potential well. Also, the generalized Lednicky-Lyuboshitz formula turned out to be broken for higher partial waves, which suggests the importance of the centrifugal force for the higher partial waves.
Comments:
23 pages, 4 figures, Proceedings of Hadron interactions with strangeness and charm, 26-28 Jun 2024
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2411.08541 [pdf]
J.Subatomic Part.Cosmol.(2025)·7 citations
06
[Submitted on 13 Nov 2024]
Correlation of the symmetry energy at subsaturation densities and neutron-skin thickness in low-energy antiproton induced reactions
Ban Zhang🇨🇳 · Zhao-Qing Feng🇨🇳
Within the framework of Lanzhou quantum molecular dynamics transport model, the neutron-skin thickness and its impact on the nuclear dynamics induced by low-energy antiprotons are investigated thoroughly. The correlation of the neutron-skin thickness and stiffness of symmetry energy is implemented into the transport model via the Fermi distributions of the proton and neutron density profiles. It is found that antiprotons are predominantly annihilated in the subsaturation density region (0.4 $ρ_{0}$ -0.8 $ρ_{0}$ ). The isospin ratios of free neutrons to protons (n/p) and charged pion yields ( $π^{-}$ / $π^{+}$ ) in collisions of antiprotons on $^{48} Ca$ and $^{208} Pb$ are analyzed systematically for extracting the symmetry energy in the domain of subsaturation densities. The n/p ratio is sensitive to the stiffness of symmetry energy in the low-density region and a soft symmetry energy leads to the larger n/p ratio, in particular with decreasing the beam momentum. The $π^{-} / π^{+}$ ratio is also enhanced with the soft symmetry energy at kinetic energies below 150 MeV.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.08619 [pdf]
PRC(2025)·2 citations
07
[Submitted on 13 Nov 2024]
Multiple shape coexistence in the $N = Z$ $^{84}$ Mo nucleus
Tomás R. Rodríguez
The structure of the nucleus $^{84}$ Mo has been studied using the projected generator coordinate method (PGCM) with the Gogny D1S interaction. The calculations incorporate a mixing of particle-number and angular-momentum projected intrinsic wave functions, defined over triaxial quadrupole degrees of freedom. This approach yields an excellent agreement with the scarce experimental data for this nucleus and several bands based on different shapes are predicted.
Comments:
submitted to the proceedings of NSD 2024
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2411.08682 [pdf]
EPJ Web Conf.(2025)·0 citations
08
[Submitted on 13 Nov 2024]
Damping of density oscillations from bulk viscosity in quark matter
José Luis Hernández🇪🇸 · Cristina Manuel🇪🇸 · Laura Tolos🇪🇸
In this contribution, we extend the discussion about the calculation of the bulk viscosity of quark matter in the normal phase due to electroweak processes and its effect on the damping of baryon density oscillations that might occur in the coalescence of two compact stars. Employing the EoSs from the MIT bag model and perturbative quantum chromodynamics (pQCD) up to $O (α_{s})$ , we analyze our results varying densities in the range of temperatures from 0 to 10 MeV for frequencies around 1 kHz. Our estimates show that bulk viscous effects might play a relevant role during the postmerger stage if the system reaches a deconfined quark matter phase.
Comments:
Contribution for the conference proceedings of the "10th International Conference on Quarks and Nuclear Physics (QNP 2024)"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2411.08710 [pdf]
PoS(2025)·0 citations
09
[Submitted on 13 Nov 2024]
Imaging Freeze-out Sources and Extracting Strong Interaction Parameters in Relativistic Heavy-Ion Collisions
Junhuai Xu🇨🇳 · Zhi Qin🇨🇳 · Renjie Zou🇨🇳 · Dawei Si🇨🇳 · Sheng Xiao🇨🇳 · Baiting Tian🇨🇳 · Yijie Wang🇨🇳 · Zhigang Xiao🇨🇳
By combining femtoscopic interferometry with an optical deblurring algorithm, we present a novel method to image the source in heavy-ion collisions (HICs) while simultaneously determining the interaction strength between particle pairs. The spatial distribution of the emission source has been reconstructed for protons ( $p$ ) and antiprotons ( $p ˉ$ ) from the respective $pp$ and $p ˉ p ˉ$ correlation functions in Au+Au collisions at $S_{NN} = 200$ GeV. Within experimental uncertainties, protons and antiprotons share the same freeze-out distribution showing higher density in the center compared to the widely assumed Gaussian shape. The results evidence the matter-antimatter symmetry in coordinate space at the moment of freeze-out before the nucleons are fully randomized in the collisions.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2411.08718 [pdf]
Chin.Phys.Lett.(2025)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE