Nuclear Theory·nucl-th

Tuesday·May 16, 2023

13 papers—8 primary·5 cross-listed

01
Neural Network predictions of inclusive electron-nucleus cross sections
O. Al Hammal🇫🇷 · M. Martini🇫🇷 · J. Frontera-Pons🇫🇷 · T. H. Nguyen🇫🇷 · R. Perez-Ramos🇫🇷
We investigate whether a neural network approach can reproduce and predict the electron-nucleus cross sections in the kinematical domain of present and future accelerator-based neutrino oscillation experiments. For this purpose, we consider the large amount of data available to the community via the web-page ``Quasielastic Electron Nucleus scattering archive'', and use a residual, fully connected feedforward neural network. We illustrate the training performances of the neural network by comparing its results with experimental data for the electron double-differential cross section on carbon. The agreement between predictions and data is remarkable from quasielastic to deep-inelastic scattering. To test the predicting power of the neural network we consider the numerous kinematical conditions for which experimental cross sections on calcium are available. Furthermore, we show the predictions of the electron scattering cross sections on oxygen, argon, and titanium: nuclei of particular interest in the context of present and future accelerator-based neutrino oscillation program. The agreement between these predictions and the data is comparable to the one of other theoretical models commonly used to calculate electron and neutrino cross sections, such as SuSAv2 and GiBUU. Results obtained with GENIE, a Monte Carlo event generator, are also discussed for comparison. The good performances obtained with our neural network suggest that neural networks could be exploited for theoretical and experimental investigations of electron- and neutrino-nucleus scattering.
nucl-thhep-exhep-phnucl-exPRC(2023)·8 citations
02
Systematic study of fusion barriers with energy dependent barrier radius
Yeruoxi Chen · Hong Yao · Min Liu · Junlong Tian · Peiwei Wen · Ning Wang
Considering energy dependence of the barrier radius in heavy-ion fusion reactions, a modified Siwek-Wilczyński (MSW) fusion cross section formula is proposed. With the MSW formula, the fusion barrier parameters for 367 reaction systems are systematically extracted, based on 443 datasets of measured cross sections. We find that the fusion excitation functions for about $60%$ reaction systems can be better described by introducing the energy dependence of the barrier radius which is due to the dynamical effects at energies near and below the barrier. Considering both the influence of the geometry radii and that of the reduced de Broglie wavelength of the colliding nuclei, the barrier heights are well reproduced with only one model parameter. The extracted barrier radius parameters linearly decrease with the effective fissility parameter, and the width of the barrier distribution relates to the barrier height and as well as the reduced de Broglie wavelength at energies around the Coulomb barrier.
nucl-thAtom.Data Nucl.Data Tabl.(2023)·11 citations
03
Resolving phase transition properties of dense matter through tidal-excited g-mode from inspiralling neutron stars
Zhiqiang Miao🇨🇳 · Enping Zhou🇨🇳 · Ang Li🇨🇳
The investigation of the phase state of dense matter is hindered by complications of first-principle nonperturbative quantum chromodynamics. By performing the first consistent general-relativistic calculations of tidal-excited g-mode of neutron stars with a first-order strong interaction phase transition in the high-density core, we demonstrate that gravitational wave signal during binary neutron star inspiral probes their innermost hadron-quark transition and provides potent constraints from present and future gravitational-wave detectors.
nucl-thastro-ph.HEgr-qchep-phApJ(2024)·24 citations
04
Sub-barrier heavy-ion fusion/capture: Accurate accounting for zero-point quadrupole shape oscillations with realistic nucleus-nucleus potential
I. I. Gontchar · M. V. Chushnyakova
Although the study of collisions of heavy ions resulting in formation of dinuclear systems has a long history this process still is a subject of experimental and scientific activities, partly because nowadays the heavy-ion fusion process is the only practical way for extending further the Periodic Table. Yet the heavy-ion capture cross sections are calculated theoretically with significant uncertainties. In particular, these cross sections below the barrier sometimes underestimate the experimental ones by orders of magnitude. In the literature, it had been shown that accounting for the Zero-Point Oscillations (ZPO) of the shape of colliding nuclei increased significantly the calculated capture cross sections. However, those calculations had been performed in a simplified way with a schematic nucleus-nucleus potential and for few reactions. The purpose of the present paper is to account for the ZPO in a more realistic way and to compare systematically the resulting capture cross sections with the experimental data. In the present paper, the nucleus-nucleus potential is evaluated using the semi-microscopical double-folding model with M3Y-Paris nucleon-nucleon forces. The nucleon densities needed for finding this potential are generated from the experimental three-parameter Fermi charge densities. The calculated capture cross sections are compared with the data for reactions 16O+54Fe, 58Ni, 144Nd, 148Sm, and 58Ni+54Fe, 58Ni, 60Ni. We show that there are certain regularities in the relationship between the experimental and theoretical cross sections with respect to the period of the quadrupole vibrations of the colliding nuclei at their ground states.
nucl-thChin.J.Phys.(2023)·2 citations
05
NN scattering with NDelta coupling: Dibaryon resonances without "dibaryons"?
J. A. Niskanen (Helsinki Institute for Physics, University of Helsinki)🇫🇮
It is known that at their threshold intermediate two-baryon NDelta states can produce resonance-like structures in some isospin one states, often interpreted as more exotic manifest six-quark states. This paper applies the coupled-channel method to study details of the NDelta effect in isospin one NN scattering with interactions constrained to exclude the influence of such extraneous hypothetical particles in two respects. Firstly, the calculated phase parameters are fitted below pion inelasticity, i.e. far below the region of "dibaryons". Secondly, the strength of the NN --> NDelta transition is constrained to agree with the pion production reaction NN --> dpi, fairly independent of the details of the pure "diagonal" NN potential and its effect practically as strong as the NN itself. The results may be considered as a necessary background for searches of additional dibaryon effects. Optimal conditions for resonant NDelta appearances involve a decrease of the orbital angular momentum in the transition NN --> NDelta, as is the case in the 1D2 and 3F3 waves. Also the effective NDelta threshold as well as its width are state dependent. Detailed complex phase shift results are presented for isospin one partial waves up to J=6, where NDelta excitation is still found to be comparable to or even larger than one pion exchange.
nucl-thnucl-exEPJA(2024)·3 citations
06
Exploring $^{3} P_{0}$ Superfluid in Dilute Spin-Polarized Neutron Matter
Hiroyuki Tajima · Hiroshi Funaki · Yuta Sekino · Nobutoshi Yasutake · Mamoru Matsuo
We explore the theoretical possibility of $^{3} P_{0}$ neutron superfluid in dilute spin-polarized neutron matter, which may be relevant to the crust region of a magnetized neutron star. In such a dilute regime where the neutron Fermi energy is less than 1 MeV, the $^{1} S_{0}$ neutron superfluid can be suppressed by a strong magnetic field of the compact star. In the low-energy limit relevant for dilute neutron matter, the $^{3} P_{0}$ interaction is stronger than the $^{3} P_{2}$ one which is believed to induce the triplet superfluid in the core. We present the ground-state phase diagram of dilute neutron matter with respect to the magnetic field and numerically estimate the critical temperature of the $^{3} P_{0}$ neutron superfluid, which is found to exceed $1 0^{7}$ K.
nucl-thastro-ph.HEcond-mat.quant-gascond-mat.supr-conPRC(2023)·8 citations
07
Baryon inhomogeneities driven charge dependent directed flow in heavy ion collisions
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳
Electromagnetic field in heavy ion collisions are expected to cause charge dependent directed flow splitting ( $Δ v_{1}$ ). Such charge dependent $Δ v_{1}$ has been observed by the STAR collaboration. We demonstrate that relativistic dissipative fluid dynamic simulations with baryon diffusion that include realistic model of baryon stopping in the initial condition and no contribution from electromagnetic field describe the measured $Δ v_{1}$ for observables involving baryons and anti-baryons. This suggests strong background contribution from baryon current as a response to initial state baryon inhomogeneities to such charge dependent $Δ v_{1}$ involving baryons and anti-baryons. Our current model calculations that only account for the evolution of the baryon charge and not electric charge and strangeness miss the observed $Δ v_{1}$ of mesons leaving their interpretation open.
nucl-thhep-phnucl-ex13 citations
08
Isospin compositions of correlated sources in the Fermi energy domain
R. Ogul · A. S. Botvina · M. Bleicher · N. Buyukcizmeci · A. Ergun · H. Imal · Y. Leifels · W. Trautmann
Isotopic yield distributions of nuclei produced in peripheral collisions of $^{80}$ Kr+ $^{40, 48}$ Ca at 35 MeV/nucleon are studied. Experimental results obtained by the FAZIA Collaboration at the LNS facility in Catania are compared with calculations performed with the statistical multifragmentation model (SMM). The fragments with atomic number $Z = 19 - 24$ observed at forward angles are successfully described with the ensemble method previously established for reactions at higher energy. Using the SMM results, the isotopic compositions of the projectile residues are reconstructed. The results indicate a significant isospin exchange between the projectile and target nuclei, not far from isospin equilibrium, during the initial phase of the reaction. The two groups of light fragments with $Z = 1 - 4$ , experimentally distinguished by their velocities relative to coincident heavy projectile fragments, are found to originate from different sources. The isotopic composition of the slower group is consistent with emission from a low-density neck, enriched in neutrons, and satisfactorily reproduced with SMM calculations for a corresponding neck source of small mass.
nucl-thnucl-exPRC(2023)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE