Nuclear Theory·nucl-th

Friday·November 8, 2024

12 papers—9 primary·3 cross-listed

01
[Submitted on 6 Nov 2024]
Cluster and anti-cluster production in heavy-ion collisions and pA reactions
Gabriele Coci🇩🇪 · Jiaxing Zhao🇮🇹 · Susanne Glässel🇩🇪 · Viktar Kireyeu🇫🇷 · Vadim Voronyuk🇷🇺 · Michael Winn🇷🇺 · Jörg Aichelin🇫🇷 · Christoph Blume🇫🇷 · Elena Bratkovskaya🇫🇷
We investigate light cluster and anti-cluster production in heavy-ion collisions from SIS to RHIC energies within the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) microscopic transport approach which propagates (anti-)baryons using n-body QMD dynamics. In PHQMD the clusters are formed dynamically by potential interactions between baryons - and recognized by the Minimum Spanning Tree (MST) algorithm - as well as by kinetic reactions in case of deuterons. We present the novel PHQMD results for different observables such as excitation functions of the multiplicity of deuterons, anti-deuterons and tritons, as well as their transverse momentum spectra. Moreover, we investigate the system size dependence of proton and deuteron production in p+A collisions and show the PHQMD results for p+A collisions (A = Be, Al, Cu, Au) at 14 AGeV/c, as well as for asymmetric Au+A collisions (A = Al, Cu, Pb) at a bombarding energy of about 10 AGeV.
Comments:
Contribution to: QNP2024
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04296 [pdf]
PoS(2025)·0 citations
02
[Submitted on 7 Nov 2024]
Dumbbell shapes in the super-asymmetric fission of heavy nuclei
F.A. Ivanyuk · N. Carjan
We have calculated the fission fragments' mass distributions for several isotopes of heavy and super-heavy nuclei from uranium to flerovium within an improved scission point model. For all considered nuclei, in addition to the standard mass-asymmetric fission mode we have found the mass super-asymmetric mode with the mass of heavy fragments equal 190. For the actinide nuclei, the probability of super-asymmetric fission is by 6 orders of magnitude smaller than for standard asymmetric fission. For the superheavy nuclei this probability is only by 2 orders of magnitude smaller. In all cases, the super-asymmetric scission shapes are dumbbells with the heavy fragment close to a sphere. We have estimated the stability of the light fragment concerning the variation of the neck and found out that sequential ternary fission is not favored energetically. The calculations were carried out with nuclear shape described by generalized Cassinian ovals with 6 deformation parameters, $α, α_{1}, α_{2}, α_{3}, α_{4}$ and $α_{5}$ . The configuration at the moment of the neck rupture was defined by fixing $α = 0.98$ . This value corresponds to a neck radius $r_{n ec k} \approx$ 1.5 fm.
Comments:
9 pages, 11 figures, submitted to PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04505 [pdf]
PRC(2024)·3 citations
03
[Submitted on 7 Nov 2024]
Inelastic electron scattering-induced nuclear excitation rates and dynamics in $^{229}$ Th
Yang-Yang Xu · Jun-Hao Cheng · You-Tian Zou · Qiong Xiao · Tong-Pu Yu
In the present work, we investigate the excitation rates and population dynamics of $^{229}$ Th nuclei induced by inelastic electron scattering, focusing on how electron energy, flux, and ionic charge state influence the excitation process of the nuclei. Using the Dirac Hartree-Fock-Slater method, we calculate cross sections for both the isomeric state (8.36 eV) and the second-excited state (29.19 keV) of $^{229}$ Th over a wide range of ionic charge states and electron energies. Our results demonstrate that these factors significantly impact the nuclear excitation efficiency. The effect of indirect excitation through the second-excited state on enhancing the accumulation of nuclei in the isomeric state cannot be ignored. By applying rate equations to model the temporal evolution of nuclear populations, we show that under optimal conditions, up to 10\% of $^{229}$ Th $^{4 +}$ ions can be accumulated in the isomeric state. These findings provide important insights for optimizing electron-nucleus interactions, contributing to the development of $^{229}$ Th-based nuclear clocks and relevant precision measurement applications.
Comments:
6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04507 [pdf]
PRC(2024)·10 citations
04
[Submitted on 7 Nov 2024]
Clusterization in nuclear states at the edge of stability
J.P. Linares Fernandez🇺🇸 · N. Michel🇨🇳 · M. Płoszajczak🇫🇷
The open quantum system eigenstate in the vicinity of low-energy decay channel may mimic its features, in particular the characteristic clustering properties of the decay channel. This generic mechanism of clusterization, the so-called mimicry mechanism of clusterization, is discussed here on example of the ground state wave function of $^{8}$ Be. At higher excitation energies, when the density of states and reaction channels is high, the quantal aspects in the clusterization process disappear and the statistical mechanism of clusterization which is rooted in the Central Limit Theorem, begin to dominate.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04617 [pdf]
EPJ Web Conf.(2024)·3 citations
05
[Submitted on 7 Nov 2024]
Spectroscopic factor calculations in the \textit{ab initio} no-core shell model
M. R. Xie · J. G. Li · N. Michel · W. Zuo
The convergence properties of spectroscopic factors in the \textit{ab initio} no-core shell model are hereby investigated. For this, we consider nuclear energies and spectroscopic factors in $A = 6$ and 7 isotopes, using the chiral forces NNLO $_{opt}$ and N $^{3}$ LO. While low-lying spectrum energy demonstrates remarkable convergence with the increase of model space within the no-core shell model, the spectroscopic factor exhibits no definitive convergence trend and seems independent of the employed nuclear interaction. The use of spectroscopic factors issued from the no-core shell model to calculate cross-sections of knockout reaction might then be questionable. The results are compared with that of the standard shell model and \textit{ab initio} Monte Carlo calculations.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04719 [pdf]
PRC(2024)·4 citations
06
[Submitted on 7 Nov 2024]
Modification of the Jet Energy-Energy Correlator in Cold Nuclear Matter
Yu Fu🇺🇸 · Berndt Müller🇺🇸 · Chathuranga Sirimanna🇺🇸
We compute medium corrections to the energy-energy correlator (EEC) for jets in electron-nucleus collisions at leading order in the QCD coupling and the interaction of the jet with the medium. We derive an analytical expression for the modification of the EEC as a function of the opening angle and show that the modification is strongest at large angles within the jet cone. We obtain explicit results for the dependence of the modification on the jet energy, the scattering power of cold nuclear matter, and the path length within the medium. We extend our calculations to gluon jets in proton-nucleus collisions and compare our results with recent preliminary data for proton-lead collisions at the LHC. We also discuss the role of comovers on the EEC in p+Pb collisions.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2411.04866 [pdf]
PRL(2025)·32 citations
07
[Submitted on 7 Nov 2024]
Variational study of Light Hypernuclei
Bhupali Sharma🇮🇳
The real nature of nucleon-hyperon and hyperon-hyperon interaction is best understood by theoretical study of single lambda hypernuclei. Variational Monte-Carlo calculations have been done on some light lambda hypernuclei using realistic NN, NNN ; phenomenological {\Lambda}N and {\Lambda}NN interactions. The results obtained for different interactions show the role of {\Lambda}N and {\Lambda}NN interactions. These interactions have been found to be important for the stability of the hypernuclear systems.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2411.04894 [pdf]
Proceedings of xth Biennial National Conf…·0 citations
08
[Submitted on 7 Nov 2024]
Effective field theories for collective excitations of atomic nuclei
E. A. Coello Pérez🇺🇸 · T. Papenbrock🇺🇸
Collective modes emerge as the relevant degrees of freedom that govern low-energy excitations of atomic nuclei. These modes - rotations, pairing rotations, and vibrations - are separated in energy from non-collective excitations, making it possible to describe them in the framework of effective field theory. Rotations and pairing rotations are the remnants of Nambu-Goldstone modes from the emergent breaking of rotational symmetry and phase symmetries in finite deformed and finite superfluid nuclei, respectively. The symmetry breaking severely constrains the structure of low-energy Lagrangians and thereby clarifies what is essential and simplifies the description. The approach via effective field theories exposes the essence of nuclear collective excitations and is defined with a breakdown scale in mind. This permits one to make systematic improvements and to estimate and quantify uncertainties. Effective field theories of collective excitations have been used to compute spectra, transition rates, and other matrix elements of interest. In particular, predictions of the nuclear matrix element for neutrinoless double beta decay then come with quantified uncertainties. This review summarizes these results and also compares the approach via effective field theories to well-known models and ab initio computations.
Comments:
84 pages, 23 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2411.04895 [pdf]
J.Phys.G(2025)·6 citations
09
[Submitted on 7 Nov 2024]
Systematic study of flow of protons and light clusters in intermediate-energy heavy-ion collisions with momentum-dependent potentials
Viktar Kireyeu🇷🇺 · Vadim Voronyuk🇷🇺 · Michael Winn🇫🇷 · Susanne Gläßel🇩🇪 · Jörg Aichelin🇫🇷 · Christoph Blume🇩🇪 · Elena Bratkovskaya🇩🇪 · Gabriele Coci🇮🇹 · Jiaxing Zhao🇩🇪
We study the influence of the nuclear equation-of-state (EoS) on collective observables -- the directed ( $v_{1}$ ) and elliptic flow ( $v_{2}$ ) of nucleons and light clusters -- in heavy-ion collisions at GeV energies using the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) approach. A novel development in this work is the inclusion of a momentum-dependent nucleon potential in the PHQMD in addition to the static, density-dependent Skyrme interaction. This enables three distinct EoS scenarios: two static ("soft" and "hard", differing in compressibility) and a soft, momentum-dependent EoS calibrated to $p A$ elastic scattering data. We find a strong EoS sensitivity in proton and cluster rapidity and $p_{T}$ distributions: soft and soft momentum-dependent EoS yield similar results, markedly different from the hard EoS. Softening the EoS reduces proton yields at midrapidity while enhancing light-cluster production. The EoS also affects flow observables differently for nucleons and clusters. For protons, a soft momentum-dependent potential increases slightly the magnitude of $v_{1}$ and $v_{2}$ relative to the hard EoS, whereas cluster flows are nearly similar. The soft momentum-dependent EoS provides an overall good agreement with experimental data from HADES and FOPI Collaborations while the soft EOS is not in line with the data. A scaling of $v_{2}$ with cluster mass number $A$ is observed at midrapidity for low $p_{T}$ , which breaks at higher $p_{T}$ . Finally, we examine the sensitivity of flow observables to deuteron production mechanisms. Deuterons formed via MST clustering exhibit different flow patterns from those produced by coalescence at freeze-out, indicating that flow harmonics may help discriminate between cluster formation scenarios.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2411.04969 [pdf]
PRC(2026)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE