Nuclear Theory·nucl-th

Tuesday·June 11, 2024

16 papers—10 primary·6 cross-listed

01
[Submitted on 7 Jun 2024]
Characterizing the nuclear models informed by PREX and CREX: a view from Bayesian inference
Tianqi Zhao · Zidu Lin · Bharat Kumar · Andrew W. Steiner · Madappa Prakash
New measurements of the weak charge density distributions of $^{48}$ Ca and $^{208}$ Pb challenge existing nuclear models. In the post-PREX-CREX era, it is unclear if current models can simultaneously describe weak charge distributions along with accurate measurements of binding energy and charge radii. In this letter, we explore the parameter space of relativistic and non-relativistic models to study the differences between the electric and weak form factors, $Δ F = F_{c h} - F_{W}$ , in $^{48}$ Ca and $^{208}$ Pb. We show, for the first time, which aspects of mean-field models are the most important in determining the relative magnitude of the neutron skin in lead and calcium nuclei. We carefully disentangle the tension between the PREX-2/CREX constraints and the ability of the RMF and Skyrme models to accurately describe binding energies and charge radii. We find that the nuclear symmetry energy coefficient $S_{V}$ and the isovector spin-orbit coefficient $b_{4}^{'}$ play different roles in determining $Δ F$ of $^{48}$ Ca and $^{208}$ Pb. Consequently, adjusting $S_{V}$ or $b_{4}^{'}$ shifts predicted $Δ F$ values toward or away from PREX-2/CREX measurements. Additionally, $S_{V}$ and the slope L are marginally correlated given the prior constraints of our Bayesian inference, allowing us to infer them separately from PREX-2/CREX data.
Comments:
6 pages, 3 figures in the letter, 11 pages, 10 figures in the supplemental material
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2406.05267 [pdf]
PRResearch(2025)·18 citations
02
[Submitted on 8 Jun 2024]
Formation of transfermium elements in reactions with $^{208}$ Pb
M. Albertsson · B.G. Carlsson · T. Døssing · J. Randrup · D. Rudolph · S. Åberg
Within the Langevin framework, we investigate the dynamics of the fusion process for production of transfermium elements in reactions of $^{48}$ Ca, $^{50}$ Ti, $^{54}$ Cr, and $^{58}$ Fe with $^{208}$ Pb. After the reacting nuclei have made contact, the early dynamical stage is dominated by the dissipation of the initial radial kinetic energy, while the subsequent shape evolution is diffusive. The probability for surmounting the inner barrier and forming a compound system is obtained by simulating the evolution as a Metropolis random walk in a five-dimensional potential-energy landscape. Good agreement with the available data is obtained, especially for the maximal formation probability.
Comments:
10 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.05330 [pdf]
PRC(2024)·2 citations
03
[Submitted on 8 Jun 2024]
Angular Momentum-Resolved Inelastic Electron Scattering for Nuclear Giant Resonances
Zhi-Wei Lu · Liang Guo · Mamutjan Ababekri · Jia-lin Zhang · Xiu-Feng Weng · Yuanbin Wu · Yi-Fei Niu · Jian-Xing Li
Giant resonances (GRs) provide crucial insights into nuclear physics and astrophysics. Exciting GRs using particles like electrons is effective, yet the angular momentum (AM) transfer of electrons, including both intrinsic spin and orbital degrees of freedom in inelastic scattering, has never been studied. Here, we investigate AM transfer in GRs excited by plane-wave and vortex electrons, developing a comprehensive AM-resolved inelastic electron scattering theory. We find that even plane-wave electrons can model-independently extract transition strengths of higher multipolarity by selecting specific AM states of scattered electrons. Additionally, relativistic vortex electrons with orbital angular momentum (OAM) $\pm 1$ can be efficiently generated. Vortex electrons can also be used to extract GR transition strength as in the plane-wave case, regardless of the position of nucleus relative to the beam axis. Furthermore, relativistic vortex electrons with larger OAM can be generated for on-axis nuclei due to AM conservation. Our method offers new perspectives for nuclear structure research and paves the way for generating vortex particles.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.05414 [pdf]
PRL(2025)·13 citations
04
[Submitted on 8 Jun 2024]
High precision measurements of alpha_s at the future EIC
T. Kutz🇺🇸 · J. R. Pybus🇺🇸 · D. W. Upton🇺🇸 · C. Cotton🇺🇸 · A. Deshpande🇺🇸 · A. Deur🇺🇸 · W.B. Li🇺🇸 · D. Nguyen🇺🇸 · M. Nycz🇺🇸 · X. Zheng🇺🇸
We present a projection study for the first moments of the inclusive spin structure function for the proton and neutron from simulated doubly-polarized e+p and e+3He collision data expected from the Electron-Ion collider. For detection and extraction of the neutron spin asymmetries from e+3He collisions, we used the double-tagging method which significantly reduces the uncertainty over the traditional inclusive method. Using the Bjorken sum rule, the projected results allow us to determine that the QCD coupling at the Z-pole alpha_s can be measured with a relative precision of 1.3%. This underscores the significance of the EIC for achieving precision determinations of alpha_s.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2406.05591 [pdf]
PRD(2024)·10 citations
05
[Submitted on 9 Jun 2024]
Spectroscopic factors of resonance states with the Gamow shell model
M.R. Xie · J.G. Li · N. Michel · H.H. Li · W. Zuo
We provide an investigation of the spectroscopic factor of resonance states in $A = 5 - 8$ nuclei, utilizing the Gamow shell model (GSM). Within the GSM, the configuration mixing is taken into account exactly with the shell model framework, and the continuum coupling is addressed via the complex-energy Berggren ensemble, which treats bound, resonance, and non-resonant continuum single-particle states on an equal footing. As a result, both the configuration mixing and continuum coupling are meticulously considered in the GSM. We first calculate the low-lying states of helium isotopes and isotones with the GSM, and the results are compared with that of \textit{ab initio} no-core shell model (NCSM) calculations. The results indicate that GSM can reproduce the low-lying resonance states more accurately than the no-core shell model. Following this, we delve into the spectroscopic factors of the resonance states as computed through both GSM and NCSM, concurrently conducting systematic calculations of overlap functions pertinent to these resonance states. Finally, the calculated overlap function and spectroscopic factor of $^{6}$ He $(0_{1}^{+})$ $\otimes ν p_{3/2} \to$ $^{7}$ He $(3/ 2_{1}^{-})$ with GSM are compared with the results from \textit{ab initio} NCSM, variational Monte Carlo, and Green's function Monte Carlo calculations, as well as avaliable experimental data. The results assert that wave function asymptotes can only be reproduced in GSM, where resonance and continuum coupling are precisely addressed.
Comments:
7 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.05640 [pdf]
SCPMA(2024)·10 citations
06
[Submitted on 9 Jun 2024]
Ab initio valence-space in-medium similarity renormalization group calculations for neutron-rich P, Cl, and K isotopes
M. R. Xie · L. Y. Shen · J. G. Li · H. H. Li · Q. Yuan · W. Zuo
Neutron-rich P, Cl, and K isotopes, particularly those with neutron numbers around $N = 28$ , have attracted extensive experimental and theoretical interest. We utilize the \textit{ab initio} valence-space in-medium similarity renormalization group approach, based on chiral nucleon-nucleon and three-nucleon forces, to investigate the exotic properties of these isotopes. Systematic calculations of the low-lying spectra are performed. A key finding is the level inversion between $3/ 2_{1}^{+}$ and $1/ 2_{1}^{+}$ states in odd- $A$ isotopes, attributed to the inversion of $π 0 d_{3/2}$ and $π 1 s_{1/2}$ single-particle states.\textit{Ab initio} calculations, which incorporate the three-nucleon forces, correlate closely with existing experimental data. Further calculations of effective proton single-particle energies provide deeper insights into the shell evolution for $Z = 14$ and $16$ sub-shells. Our results indicate that the three-body force plays important roles in the shell evolution for $Z = 14$ and $16$ sub-shells with neutron numbers ranging from 20 to 28. Additionally, systematic \textit{ab initio} calculations are conducted for the low-lying spectra of odd-odd nuclei. The results align with experimental data and provide new insights for future research into these isotopes, up to and beyond the drip line.
Comments:
12 pages, 9 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.05669 [pdf]
CPC(2024)·1 citation
07
[Submitted on 9 Jun 2024]
Thermodynamically consistent accreted crust of neutron stars: The role of proton shell effects
Mikhail E. Gusakov · Andrey I. Chugunov
Observations of accreting neutron stars are widely used to constrain the microphysical properties of superdense matter. A key ingredient in this analysis is the heating associated with nuclear reactions in the outer layers of the neutron star (crust), as well as the equation of state and composition of these layers. As recently shown, the neutron hydrostatic/diffusion (nHD) condition is valid in the inner part of the crust, where some of the neutrons are not bound to the nuclei, and this condition should be properly incorporated into crustal models. Here we construct models of the accreted crust of a neutron star, taking into account the nHD condition and proton shell effects in nuclei. For numerical illustration, we employ the recently proposed compressible liquid drop model, which incorporates shell effects. However, our approach is general and can also be used in future studies relying on more sophisticated nuclear physics models.
Comments:
20 pages, 8 figures, accepted for publication in Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2406.05680 [pdf]
PRD(2024)·4 citations
08
[Submitted on 9 Jun 2024]
Relativistic Corrections to the CBF Effective Nuclear Hamiltonian
Andrea Sabatucci · Omar Benhar · Alessandro Lovato
We discuss the inclusion of relativistic boost corrections into the CBF effective nuclear Hamiltonian, derived from a realistic model of two- and three-nucleon interactions using the formalism of correlated basis functions and the cluster expansion technique. Different procedures to take into account the effects of boost interactions are compared on the basis of the ability to reproduce the nuclear matter equation of state obtained from accurate many-body calculations. The results of our study show that the repulsive contribution of the boost interaction significantly depends on the underlying model of the non relativistic potential. On the other hand, the dominant relativistic correction turns out to be the corresponding reduction of the strength of repulsive three-nucleon interactions, leading to a significant softening of the equation of state at supranuclear densities.
Comments:
Few changes to match the version published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2406.05732 [pdf]
PRC(2024)·2 citations
09
[Submitted on 10 Jun 2024]
Feasibility of the observation of $η^{'}$ mesic nuclei in the semi-exclusive $^{12}$ C( $p, d p$ ) reaction
Natsumi Ikeno🇯🇵 · Yuko Higashi🇯🇵 · Hiroyuki Fujioka🇯🇵 · Kenta Itahashi🇯🇵 · Ryohei Sekiya🇯🇵 · Yoshiki K. Tanaka🇯🇵 · Junko Yamagata-Sekihara🇯🇵 · Volker Metag🇩🇪 · Mariana Nanova🇩🇪 · Satoru Hirenzaki🇯🇵
We study theoretically the feasibility of the semi-exclusive $^{12}$ C( $p, d p$ ) $X$ reaction for the observation of $η^{'}$ mesic nuclei using the microscopic transport model JAM. The semi-exclusive measurements of the ( $p, d$ ) reaction with protons from $η^{'}$ absorption are found to be significant for the observation of the $η^{'}$ bound states. Especially, the measurements of the energetic protons from $η^{'}$ non-mesic two-body absorption ( $η^{'} N N \to N N$ ) are considered to be critically important. The Green's function method is used to calculate the expected spectrum of forward going deuterons corresponding to the excitation energy spectrum of the $η^{'} \otimes^{11}$ C system in the semi-exclusive measurement. The semi-exclusive measurements are shown to be important in general for the $η^{'}$ mesic nucleus observation.
Comments:
11 pages, 5 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2406.06058 [pdf]
PTEP(2026)·7 citations
10
[Submitted on 10 Jun 2024]
Modeling inclusive electron-nucleus scattering with Bayesian artificial neural networks
Joanna E. Sobczyk🇩🇪 · Noemi Rocco🇺🇸 · Alessandro Lovato🇺🇸
We introduce a Bayesian protocol based on artificial neural networks that is suitable for modeling inclusive electron-nucleus scattering on a variety of nuclear targets with quantified uncertainties. Unlike previous applications in the field, which directly parameterize the cross sections, our approach employs artificial neural networks to represent the longitudinal and transverse response functions. In contrast to cross sections, which depend on the incoming energy, scattering angle, and energy transfer, the response functions are determined solely by the energy and momentum transfer to the system, allowing the angular component to be treated analytically. We assess the accuracy and predictive power of our framework against the extensive data in the quasielastic inclusive electron-scattering database. Additionally, we present novel extractions of the longitudinal and transverse response functions and compare them with previous experimental analysis and nuclear ab-initio calculations.
Comments:
9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
2406.06292 [pdf]
PLB(2024)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE