Nuclear Theory·nucl-th

Tuesday·November 19, 2024

21 papers—9 primary·12 cross-listed

01
Effect of the near-proton-emission threshold resonance in $^{11}$ B on the branching ratio of beta-delayed proton emission from $^{11}$ Be
Nguyen Le Anh · Bui Minh Loc
Beta-delayed proton emission from neutron halo nuclei $^{11} Be$ represents a rare decay process. The existence of the narrow resonance near the proton-emission threshold in $^{11} B$ explains its unexpectedly high probability. However, the accurate value of the branching ratio remains challenging to determine. We aim to quantify the influence of the narrow resonance near the proton emission threshold on the result of the branching ratio. We employ the Skyrme Hartree-Fock calculation within the potential model to obtain the branching ratio. We derive the single-particle potentials for the halo neutron and the emitting proton with minimal adjustment. Slight variations in the resonance position significantly impact the branching ratio, with the upper limit reaching the order of $1 0^{- 5}$ . Experimental determination of the resonance energy, particularly whether it lies below $200$ keV, is crucial for determining the value of the branching ratio.
nucl-thnucl-exJ.Phys.G(2026)·0 citations
02
Neutron-rich isotope production for $Z \geq 98$ in $^{238} U +^{248} Cm$ reaction
S.E. Ocal · O. Yilmaz · S. Ayik · A. S. Umar
Background: Multi-nucleon transfer (MNT) reactions in actinide systems are a promising method to synthesize transuranium neutron-rich elements. Appropriate theoretical approaches are needed to understand the mechanism behind MNT. Purpose: This work aims to produce neutron-rich isotopes in the super-heavy region through the $^{238} U +^{248} Cm$ system. We employ a microscopic approach to elucidate reaction mechanisms, and predict new isotope production that expands the known nuclear chart. Methods: The stochastic mean-field (SMF) approach, including fluctuations and correlations, is used to explain the primary cross-sections in MNT reactions based on the quasi-fission and inverse quasi-fission processes, and a statistical de-excitation model with GEMINI++ code to calculate the secondary fragment cross-sections Results: The calculated cross-sections using SMF and GEMINI++ explain available experimental results for the $^{238} U +^{248} Cm$ system at $E_{c.m.} = 898.7$ ~MeV energy. This shows the effectiveness and applicability of the quantal diffusion approach based on the SMF theory in heavy-ion collisions. Conclusions: Production of transuranium neutron-rich elements with a proton number up to $Z =$ 101 are obtained with sizable cross-sections. Theoretical results calculated for the Z=102-105 region, for which there are no experimental data, show that the cross-section values would be lower than the microbarn level. SMF theory does not contain any adjustable parameters other than the standard parameters of the energy density functional used in the TDHF theory and is an important approach for the microscopic understanding of reaction mechanisms.
nucl-th0 citations
03
Fragmentation of Nuclear Remnants in Electron-Nucleus Collisions at High Energy as a Nonextensive Process
Ting-Ting Duan🇨🇳 · Sahanaa Büriechin🇨🇳 · Hai-Ling Lao🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
Utilizing a partitioning method based on equal (or unequal) probabilities -- without incorporating the alpha-cluster ( $α$ -cluster) model -- allows for the derivation of diverse topological configurations of nuclear fragments resulting from fragmentation. Subsequently, we predict the multiplicity distribution of nuclear fragments for specific excited nuclei, such as $^{9}$ Be $^{*}$ , $^{12}$ C $^{*}$ , and $^{16}$ O $^{*}$ , which can be formed as nuclear remnants in electron-nucleus ( $e A$ ) collisions at high energy. Based on the $α$ -cluster model, an $α$ -cluster structure may result in deviations in the multiplicity distributions of nuclear fragments with charge $Z = 2$ , compared to those predicted by the partitioning methods. Furthermore, in the framework of Tsallis statistics, the nonextensive generalized temperature, entropy index, and $q$ -entropy are obtained from the multiplicity distribution of nuclear fragments with given charge number. Our work shows that fragmentation of nuclear remnants in electron-nucleus collisions at high energy is a nonextensive process.
nucl-thnucl-exEntropy(2026)·0 citations
04
On variational trial functions in the extended Thomas-Fermi method
A. Y. Potekhin · A. I. Chugunov · N. N. Shchechilin · N. Chamel
Parametrized nucleon density distributions are widely employed for the calculation of the properties of atomic nuclei and dense inhomogeneous matter in compact stars within the Thomas-Fermi method and its extensions. We show that the use of insufficiently smooth parametrizations may deteriorate the accuracy of this method. We discuss and clarify the smoothness condition using the example of the so-called "nuclear pasta" in the neutron star mantle.
nucl-thastro-ph.HEPhys.Usp.(2025)·2 citations
05
Quadrupole-hexadecapole correlations in neutron-rich samarium and gadolinium isotopes
L. Lotina · K. Nomura · R. Rodríguez-Guzmán · L.M. Robledo
We present an extensive study of quadrupole-hexadecapole correlation effects in even-even Sm and Gd isotopes with neutron number $N = 88 - 106$ . The calculations are performed in the framework of the Gogny energy density functional (EDF) with the D1S parametrization and the $s d g$ interacting boson model (IBM). The quadrupole-hexadecapole constrained self-consistent mean-field potential energy surface is mapped onto the expectation value of the $s d g$ -boson Hamiltonian. This procedure determines the parameters of the $s d g$ -IBM Hamiltonian microscopically. Calculated excitation energies and transition strengths are compared to the ones obtained with a simpler $s d$ -IBM, as well as with the experimental data. The Gogny-EDF mapped $s d g$ -IBM reproduces spectroscopic properties of the studied nuclei as reasonably as in the case of the previous $s d g$ -boson mapping calculations that were based on the relativistic EDF, indicating that the axial quadrupole-hexadecapole method is sound regardless of whether relativistic or nonrelativistic EDF is employed. The mapped $s d g$ -IBM improves some of the results in lighter Sm and Gd isotopes compared to the mapped $s d$ -IBM, implying the existence of significant hexadecapole correlations in those nuclei. For those nuclei with $N \geq 94$ , hexadecapole effects are minor, and the only significant difference between the two boson models can be found in the description of $E 0$ monopole transitions.
nucl-thnucl-exPRC(2025)·7 citations
06
1+1 dimensional relativistic viscous non-resistive magnetohydrodynamics with longitudinal boost invariance
Ze-Fang Jiang🇨🇳 · Shuo-Yan Liu🇨🇳 · Tian-Yu Hu🇨🇳 · Huang-Jing Zheng🇨🇳 · Duan She🇨🇳
We study 1+1 dimensional relativistic non-resistive magnetohydrodynamics (MHD) with longitudinal boost invariance and shear stress tensor. Several analytical solutions that describe the fluid temperature evolution under the equation of state (EoS) $ε = 3 p$ are derived, relevant to relativistic heavy-ion collisions. Extending the Victor-Bjorken ideal MHD flow to include non-zero shear viscosity, two perturbative analytical solutions for the first-order (Navier-Stokes) approximation are obtained. For small, power-law evolving external magnetic fields, our solutions are stable and show that both magnetic field and shear viscosity cause fluid heating with an early temperature peak, align with the numerical results. In the second-order (Israel-Stewart) theory, our findings show that the combined presence of magnetic field and shear viscosity leads to a slow cooling rate of fluid temperature, with initial shear stress significantly affecting temperature evolution of QGP.
nucl-thhep-phCPC(2025)·4 citations
07
Fermionic Neural Networks through the lens of Group Theory
J. Rozalén Sarmiento · A. Rios
We present an overview of the method of Neural Quantum States applied to the many-body problem of atomic nuclei. Through the lens of group representation theory, we focus on the problem of constructing neural-network ansätze that respect physical symmetries. We explicitly prove that determinants, which are among the most common methods to build antisymmetric neural-network wave functions, can be understood as the result of a group convolution. We also identify the reason why this construction is so efficient in practice compared to other group convolutional operations. We conclude that group representation theory is a promising avenue to incorporate explicitly symmetries in Neural Quantum States.
nucl-thquant-phPoS(2025)·0 citations
08
$Λ N N$ input to neutron stars from hypernuclear data
Eliahu Friedman🇮🇱 · Avraham Gal🇮🇱
This work is a sequel to our two 2023 publications [PLB 837 137669, NPA 1039 122725] where fitting 14 1 $s_{Λ}$ and 1 $p_{Λ}$ single-particle binding energies in hypernuclei across the periodic table led to a well-defined $Λ$ -nucleus optical potential. The potential consists of a Pauli modified linear-density ( $Λ N$ ) and a quadratic-density ( $Λ N N$ ) terms. The present work reports on extending the above analysis to 21 $Λ$ single-particle data points input by including 1 $d_{Λ}$ and 1 $f_{Λ}$ states in medium-weight and heavy hypernuclei. The upgraded results for the $Λ N$ and $Λ N N$ potential depths at nuclear-matter density $ρ_{0} = 0.17$ ~fm $^{- 3}$ , $D_{Λ}^{(2)} = - 37.5 \mp 0.7$ ~MeV and $D_{Λ}^{(3)} = + 9.8 \pm 1.2$ ~MeV together with the total depth $D_{Λ} = - 27.7 \pm 0.5$ ~MeV, agree within errors with the earlier results. The $Λ$ hypernuclear overbinding associated with the $Λ N$ -induced potential depth $D_{Λ}^{(2)}$ agrees quantitatively with a recent combined analysis of low-energy $Λ p$ scattering data and correlation functions [PLB 850 (2024) 138550]. These results, particularly the size of the repulsive $D_{Λ}^{(3)}$ , provide an essential input towards resolving the 'hyperon puzzle' in the core of neutron stars. We also show that a key property of our $Λ N N$ -induced potential term, i.e. a need to suppress the quadratic-density $Λ N N$ term involving an excess neutron and a $N = Z$ core nucleon, can be tested in the forthcoming JLab E12-15-008 experiment.
nucl-thnucl-exPoS(2025)·5 citations
09
An introduction to relativistic spin hydrodynamics
Xu-Guang Huang🇨🇳
Spin polarization and spin transport are common phenomena in many quantum systems. Relativistic spin hydrodynamics provides an effective low-energy framework to describe these processes in quantum many-body systems. The fundamental symmetry underlying relativistic spin hydrodynamics is angular momentum conservation, which naturally leads to inter-conversion between spin and orbital angular momenta. This inter-conversion is a key feature of relativistic spin hydrodynamics, closely related to entropy production and introducing ambiguity in the construction of constitutive relations. In this article, we present a pedagogical introduction to relativistic spin hydrodynamics. We demonstrate how to derive the constitutive relations by applying local thermodynamic laws and explore several distinctive aspects of spin hydrodynamics. These include the pseudo-gauge ambiguity, the behavior of the system in the presence of strong vorticity, and the challenges of modeling the freeze-out of spin in heavy-ion collisions. We also outline some future prospects for spin hydrodynamics.
nucl-thhep-phnucl-exphysics.flu-dynNucl.Sci.Tech.(2025)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE