Nuclear Theory·nucl-th

Wednesday·October 18, 2023

11 papers—6 primary·5 cross-listed

01
[Submitted on 16 Oct 2023]
Electric dipole polarizability of low-lying excited states in atomic nuclei
José Nicolás Orce · Cebo Ngwetsheni
Novel equations for the electric dipole polarizability $α_{_{E 1}}$ of low-lying excited states in atomic nuclei -- and the related $(- 2)$ moment of the total photo-absorption cross section, $σ_{_{- 2}}$ -- are inferred in terms of electric dipole and quadrupole matrix elements. These equations are valid for arbitrary angular momenta of the initial/ground and final/excited states and have been exploited in fully converged 1 $ℏ ω$ shell-model calculations of selected {\it p-} and {\it sd-}shell nuclei that consider configuration mixing; advancing previous knowledge from $^{17}$ O to $^{36}$ Ar, where thousands of electric dipole matrix elements are computed from isovector excitations which include the giant dipole resonance region. Our results are in reasonable agreement with previous shell-model calculations and follow -- except for $^{6, 7}$ Li and $^{17, 18}$ O -- Migdal's global trend provided by the combination of the hydrodynamic model and second-order non-degenerate perturbation theory. Discrepancies in $^{6, 7}$ Li and $^{17}$ O arise as a result of the presence of $α$ -cluster configurations in odd-mass nuclei, whereas the disagreement in $^{18}$ O comes from the mixing of intruder states, which is lacking in the shell-model interactions. More advanced \emph{ab initio} calculations of the dipole polarizability for low-lying excited states covering all the isovector states within the giant dipole resonance region are missing and could be very valuable to benchmark the results presented here and shed further light on how atomic nuclei polarize away from the ground state
Comments:
8 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2310.10775 [pdf]
J.Phys.G(2024)·4 citations
02
[Submitted on 16 Oct 2023]
Viscosities of the Baryon-Rich Quark-Gluon Plasma from Beam Energy Scan Data
Chun Shen🇺🇸 · Björn Schenke🇺🇸 · Wenbin Zhao🇺🇸
This work presents the first Bayesian inference study of the (3+1)D dynamics of relativistic heavy-ion collisions and Quark-Gluon Plasma (QGP) viscosities using an event-by-event (3+1)D hydrodynamics + hadronic transport theoretical framework and data from the Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan program. Robust constraints on initial state nuclear stopping and the baryon chemical potential-dependent shear viscosity of the produced quantum chromodynamic (QCD) matter are obtained. The specific bulk viscosity of the QCD matter is found to exhibit a preferred maximum around $s_{NN} = 19.6$ GeV. This result allows for the alternative interpretation of a reduction (and/or increase) of the speed of sound relative to that of the employed lattice-QCD based equation of state (EOS) for net baryon chemical potential $μ_{B} \sim 0.2 (0.4)$ GeV.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2310.10787 [pdf]
PRL(2024)·42 citations
03
[Submitted on 17 Oct 2023]
A Data-Driven Density Functional Model for Nuclear Systems
Zu-Xing Yang · Xiao-Hua Fan · Zhi-Pan Li · Haozhao Liang
Through ensemble learning with multitasking and complex connection neural networks, we aggregated nuclear properties, including ground state charge radii, binding energies, and single-particle state information obtained from the Kohn-Sham auxiliary single-particle systems. Compared to traditional density functional theory, our model can more accurately characterize nuclear ground state information. Aiming at binding energy, the root mean square error is reduced to 450 keV. Although the complexity involving the nuclear interaction is skipped, the model has not completely devolved into a black box. Leveraging the correlation between densities and binding energies, we calculate the neutron skin thickness of $^{208}$ Pb to be 0.223 fm. This model will advance our understanding of nuclear properties and accelerate the integration of machine learning into modern nuclear physics.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2310.11012 [pdf]
PRC(2024)·3 citations
04
[Submitted on 17 Oct 2023]
$R$ -dependence of jet observables with JEWEL+v-USPhydro
Leonardo Barreto🇧🇷 · Fabio M. Canedo🇧🇷 · Maria M. M. Paulino🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Jorge Noronha🇺🇸 · Marcelo G. Munhoz🇧🇷
The $R$ -dependence of jet observables provides a new tool in understanding the interplay between the jet energy-loss mechanism and medium response in heavy-ion collisions. This work applies the Monte Carlo events generator JEWEL and PYTHIA, coupled with $T_{R} ENTo$ initial conditions and the state-of-the-art (2+1)D v-USPhydro, for the simulation of jet distributions and substructure observables for lead-lead collisions at LHC energy scales. We present the jet nuclear modification $R_{AA}$ and anisotropic flow coefficients $v_{n = 2, 3}$ varying the jet cone radius $R$ , in the context of anti- $k_{T}$ jets, in addition to leading subjet fragmentation. The calculations indicate the impacts of the hydrodynamic evolution and weakly-coupled medium response, given by recoils, on the distributions. Results are compared to experimental data in a wide range of jet $p_{T}$ and collision centrality, and displayed along large jets ( $R \geq 0.6$ ) predictions.
Comments:
6 pages, 4 figures, contribution to the proceedings of the 11th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2023), Aschaffenburg (Germany), March 26-31, 2023. Submitted to PoS
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2310.11150 [pdf]
PoS(2024)·0 citations
05
[Submitted on 17 Oct 2023]
Conservation Laws and Hydrodynamics
Sangyong Jeon🇨🇦
Recent years have seen much development in analyzing the structure of relativistic hydrodynamics. In this proceeding, some of the developments are highlighted including issues related to pseudo-gauge transformations and spin hydrodynamics.
Comments:
6 pages. A contribution to 20th International Conference on Strangeness in Quark Matter 2022(SQM2022)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2310.11269 [pdf]
EPJ Web Conf.(2023)·4 citations
06
[Submitted on 17 Oct 2023]
Is $K_{1} / K^{*}$ enhancement in heavy ion collisions a signature of chiral symmetry restoration?
Haesom Sung🇰🇷 · Sungtae Cho🇰🇷 · Che Ming Ko🇺🇸 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷
We extend the recent study of $K_{1} / K^{*}$ enhancement as a signature of chiral symmetry restoration in heavy ion collisions at the Large Hadron Collider (LHC) via the kinetic approach to include the effects due to non-unity hadron fugacities during the evolution of produced hadronic matter and the temperature-dependent $K_{1}$ mass. Although the effect of non-unity fugacity only slightly reduces the $K_{1} / K^{*}$ enhancement due to chiral symmetry restoration, the inclusion of the temperature-dependent $K_{1}$ mass leads to a substantial reduction in the $K_{1} / K^{*}$ enhancement. However, the final $K_{1} / K^{*}$ ratio in peripheral collisions still shows a more than factor of two enhancement compared to the case without chiral symmetry restoration and thus remains a good signature for chiral symmetry restoration in the hot dense matter produced in relativistic heavy ion collisions.
Comments:
5 pages with 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2310.11434 [pdf]
PoS(2025)·11 citations
07
[Submitted on 16 Oct 2023] (cross-list from hep-ph)
Multi-dimensional hadron structure through the lens of gluon Wigner distribution
Roman Pasechnik🇸🇪 · Marek Taševský🇨🇿
In this review, we present the current status of phenomenological research on constraining the multi-dimensional proton (and nucleus) structure at high energies through studies of the so-called gluon Wigner distributions. We provide a brief pedagogical introduction into the corresponding theoretical definitions and modelling of exclusive and diffractive scattering observables in terms of the Wigner distribution. Also, we present a detailed outlook into the existing and planned experimental measurements that attempt to constrain the Wigner distribution. We briefly overview possible interconnections between various manifestations of the gluon Wigner distribution emerging, for instance, in azimuthal-angle correlations in (semi)exclusive reactions and elliptic flow measurements in inclusive processes. We also summarise the current knowledge on the most important processes that would potentially enable one to constrain the elliptic gluon density in the proton and to separate it from the genuine effect of hydrodynamic evolution in the flow measurements.
Comments:
75 pages, 18 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2310.10793 [pdf]
Phys.Rept.(2024)·17 citations
08
[Submitted on 16 Oct 2023] (cross-list from astro-ph.HE)
Assessing equation of state-independent relations for neutron stars with nonparametric models
Isaac Legred🇺🇸 · Bubakar O. Sy-Garcia🇺🇸 · Katerina Chatziioannou🇺🇸 · Reed Essick🇨🇦
Relations between neutron star properties that do not depend on the nuclear equation of state offer insights on neutron star physics and have practical applications in data analysis. Such relations are obtained by fitting to a range of phenomenological or nuclear physics equation of state models, each of which may have varying degrees of accuracy. In this study we revisit commonly-used relations and re-assess them with a very flexible set of phenomenological nonparametric equation of state models that are based on Gaussian Processes. Our models correspond to two sets: equations of state which mimic hadronic models, and equations of state with rapidly changing behavior that resemble phase transitions. We quantify the accuracy of relations under both sets and discuss their applicability with respect to expected upcoming statistical uncertainties of astrophysical observations. We further propose a goodness-of-fit metric which provides an estimate for the systematic error introduced by using the relation to model a certain equation-of-state set. Overall, the nonparametric distribution is more poorly fit with existing relations, with the I-Love-Q relations retaining the highest degree of universality. Fits degrade for relations involving the tidal deformability, such as the Binary-Love and compactness-Love relations, and when introducing phase transition phenomenology. For most relations, systematic errors are comparable to current statistical uncertainties under the nonparametric equation of state distributions.
Comments:
21 pages, 13 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2310.10854 [pdf]
PRD(2024)·19 citations
09
[Submitted on 17 Oct 2023] (cross-list from hep-ph)
Kaon Structure in the Nuclear Medium within the Light Front Approach
G. H. S. O. Yabusaki (Universidade São Judas Tadeu, Universidade Cruzeiro do Sul and Universidade Cidade de São Paulo, Brazil)🇧🇷 · J. P. B. C. de Melo (Universidade Cruzeiro do Sul and Universidade Cidade de São Paulo, Brazil)🇧🇷 · K. Tsushima (Universidade Cruzeiro do Sul and Universidade Cidade de São Paulo, Brazil)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica, Brazil)🇧🇷 · W. de Paula (Instituto Tecnológico de Aeronáutica, Brazil)🇧🇷
We study the properties of the charged kaon in symmetric nuclear matter using a Bethe-Salpeter amplitude to model the quark-anti-quark bound state, which is well constrained by previous studies of its vacuum properties. The electromagnetic form factor, charge radius, decay constant and the light-front valence component probability are investigated in symmetric nuclear matter. In order to describe the constituent up and anti-strange quarks in nuclear matter, we adopt the ``quark-meson coupling (QMC) model", which has been widely applied to various hadronic and nuclear phenomena in the nuclear medium.
Comments:
11 pages, 16 figures, revtex4 style. arXiv admin note: text overlap with arXiv:1404.5873
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2310.11262 [pdf]
PRD(2024)·8 citations
10
[Submitted on 17 Oct 2023] (cross-list from nucl-ex)
Reactions induced by 30 MeV 3He beam on 9Be: Cluster transfer reactions
Urazbekov Bakytzhan · Issatayev Talgat · Lukyanov Sergey · Azhibekov Aidos · Denikin Andrey · Mendibayev Kayrat · Janseitov Daniyar · Penionzhkevich Yuri · Kuterbekov Kayrat · Zholdybayev Timur
An experiment has been carried out for studying the cluster structure of $^{9}$ Be induced by the $^{3}$ He ions at the energy of 30 MeV. As results of the nuclear reaction $^{3}$ He + $^{9}$ Be the differential cross sections for the exit channels - elastic, inelastic, $α$ + $^{8}$ Be, $^{6}$ He + $^{6}$ Be, $^{6}$ Li + $^{6}$ Li, and $^{7}$ Be + $^{5}$ He - were measured. Elastic and inelastic scattering data are treated within both the optical model and Coupled channels method. A new set of optical potential was taken for the elastic scattering. The deformation parameter $δ_{2}$ was established for the transition $3/2 \to 5/2$ . Cluster transfer reactions are analyzed by means of the coupled reaction channels method. The nuclear reactions with the exit channels $^{6}$ He + $^{6}$ Be, $^{6}$ Li + $^{6}$ Li, and $^{7}$ Be + $^{5}$ He are complemented by two-step transfer mechanisms. The contribution of each reaction mechanisms are shown, and compared with the findings of other authors.
Comments:
13 pages, 11 figures,1 table
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2310.11306 [pdf]
CPC(2024)·4 citations
11
[Submitted on 17 Oct 2023] (cross-list from hep-ph)
Dark matter scattering off $^{4}$ He in chiral effective field theory
J. de Vries🇳🇱 · C. Körber🇩🇪 · A. Nogga🇩🇪 · S. Shain🇳🇱
We study dark matter scattering off $^{4}$ He and other light nuclei using chiral effective field theory. We consider scalar DM interactions and include both one- and two-nucleon scattering processes. The DM interactions and nuclear wave functions are obtained from chiral effective field theory and we work up to fourth order in the chiral expansion for the latter to investigate the chiral convergence. The results for the scattering rates can be used to determine the sensitivity of planned experiments to detect relatively light dark matter particles using $^{4}$ He. We find that next-to-leading-order scalar currents are smaller than expected from power counting for scattering off $^{4}$ He confirming earlier work. However, the results for two-nucleon corrections exhibit a linear regulator dependence indicating potential problems in the applied power counting. We observe a linear correlation between the, in principle not observable, D-wave probability of various light nuclei and the scalar two-nucleon matrix elements, again pointing towards potentially missing contributions.
Comments:
18 pages, 8 figures, as published in EPJ C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2310.11343 [pdf]
EPJC(2024)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE