Nuclear Theory·nucl-th

Tuesday·March 7, 2023

15 papers—7 primary·8 cross-listed

01
[Submitted on 4 Mar 2023]
Dynamical mechanisms for deuteron production at mid-rapidity in relativistic heavy-ion collisions from SIS to RHIC energies
Gabriele Coci🇩🇪 · Susanne Gläßel🇩🇪 · Viktar Kireyeu🇩🇪 · Jörg Aichelin🇫🇷 · Christoph Blume🇩🇪 · Elena Bratkovskaya🇩🇪 · Vadim Kolesnikov🇷🇺 · Vadim Voronyuk🇩🇪
The understanding of the mechanisms for the production of weakly bound clusters, such as a deuteron $d$ , in heavy-ion reactions at mid-rapidity is presently one of the challenging problems which is also known as the "ice in a fire" puzzle. In this study we investigate the dynamical formation of deuterons within the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) microscopic transport approach and advance two microscopic production mechanisms to describe deuterons in heavy-ion collisions from SIS to RHIC energies: kinetic production by hadronic reactions and potential production by the attractive potential between nucleons. Differently to other studies, for the "kinetic" deuterons we employ the full isospin decomposition of the various $π N N \leftrightarrow π d$ , $N N N \leftrightarrow N d$ channels and take into account the finite size properties of the deuteron by means of an excluded volume condition in coordinate space and by the projection onto the deuteron wave function in momentum space. We find that considering the quantum nature of the deuteron in coordinate and momentum space reduces substantially the kinetic deuteron production in a dense medium as encountered in heavy-ion collisions. If we add the "potential" deuterons by applying an advanced Minimum Spanning Tree (aMST) procedure, we obtain good agreement with the available experimental data from SIS energies up to the top RHIC energy.
Comments:
35 pages, 24 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.02279 [pdf]
PRC(2023)·43 citations
02
[Submitted on 5 Mar 2023]
Octupole deformation of nuclei near the spherical closed-shell configurations
Ken-ichiro Arita
The origin of octupole deformation for even-even nuclei near the doubly-closed shell configurations are investigated by means of the semiclassical periodic orbit theory. In order to focus on the change of shell structure due to deformation, a simple infinite-well potential model is employed with octupole shape parametrized by merging a sphere and a paraboloid. Attention is paid to the contributions of the degenerate families of periodic orbits (POs) confined in the spherical portion of the potential, that are expected to partially preserve the spherical shell effect up to considerably large value of the octupole parameter. The contribution of those POs to the semiclassical trace formula plays an important role in bringing about shell energy gain due to octupole deformation in the system with a few particles added to spherical closed-shell configurations.
Comments:
accepted version for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.02701 [pdf]
PRC(2023)·2 citations
03
[Submitted on 5 Mar 2023]
Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics
K. Pomorski🇵🇱 · B. Nerlo-Pomorska🇵🇱 · C. Schmitt🇫🇷 · Z.G. Xiao🇨🇳 · Y. J. Chen🇨🇳 · L.L. Liu🇨🇳
We propose a new, rapidly convergent, the so-called Fourier over Spheroid (FoS), shape parametrization to model fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system, being its elongation, left-right asymmetry, neck size, and non-axiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on the top of which the multi-dimensional Langevin equation is solved to describe the dynamics. Charge equilibration at scission and de-excitation of the primary fragments after scission are further considered. The model gives access to a wide variety of observables, including fission fragments mass, charge, and kinetic energy yields, fragment mean N/Z and post-scission neutron multiplicities, and importantly, their correlations. The latter are crucial to unravel the complexity of the fission process. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of 235U, and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain.
Comments:
15th pages, 18 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2303.02774 [pdf]
PRC(2023)·20 citations
04
[Submitted on 6 Mar 2023]
Description of inclusive $(d, d^{'} x)$ reaction with the semiclassical distorted wave model
Hibiki Nakada · Kazuki Yoshida · Kazuyuki Ogata
The description of deuteron-induced inclusive reactions has been an important subject in direct nuclear reaction studies and nuclear data science. For proton-induced inclusive processes, the semiclassical distorted wave model (SCDW) is one of the most successful models based on quantum mechanics. We improve SCDW for deuteron-induced inclusive processes and clarify the importance of the proper treatment of the kinematics of the deuteron inside a nucleus. The double differential cross section (DDX) of the inclusive deuteron-emission process $(d, d^{'} x)$ is described by one-step SCDW. The changes in the kinematics due to the distortion effect, the refraction effect, is taken into account by the local semiclassical approximation (LSCA). The calculated DDXs of $(d, d^{'} x)$ reasonably reproduce experimental data in the small energy-transfer region and at forward and middle angles with some exceptions. The angular distributions of $(d, d^{'} x)$ are improved by including the refraction effect. The proper treatment of the changes in the kinematics of the deuteron inside a nucleus is necessary in describing the ( $d$ , $d^{'} x$ ) reaction. The effect of the changes on the DDX of $(d, d^{'} x)$ is significant compared to on the proton-induced inclusive process $(p, p^{'} x)$ because of the stronger distortion effect on the deuteron.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2303.02985 [pdf]
PRC(2023)·4 citations
05
[Submitted on 6 Mar 2023]
A Crossover phase transition based on the phenomenology of hadronic matter and quark matter
Mahboubeh Shahrbaf🇵🇱
The phase transition calculations are utilized for an in-depth understanding of the thermodynamics of the deconfinement transition to perform the best analysis of the QCD phase diagram. The phenomenological justifications for a mathematical approach to constructing the phase transition are found based on the properties of hadronic matter at low densities as well as quark matter at high densities. We modify both the quark matter equation of state by confining effects at low densities and the hadronic matter equation of state by excluded volume effects at higher densities. Over the intermediate densities, the transition from the hadronic phase to the quark phase is modified by the surface tension between to phases. The results are in agreement with the observational constraints of neutron stars.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.03030 [pdf]
0 citations
06
[Submitted on 2 Mar 2023]
Excitation functions of related temperatures of {\eta} and {\eta}0 emission sources from squared momentum transfer spectra in high-energy collisions
Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The squared momentum transfer spectra of $η$ and $η^{0}$ , produced in high-energy photon-proton ( $γ p$ ) $\to η (η^{0}) + p$ processes in electron-proton ( $e p$ ) collisions performed at CEBAF, NINA, CEA, SLAC, DESY, and WLS are analyzed. The Monte Carlo calculations are used in the analysis of the squared momentum transfer spectra, where the transfer undergoes from the incident $γ$ to emitted $η (η^{0})$ or equivalently from the target proton to emitted proton. In the calculations, the Erlang distribution and Tsallis-Levy function are used to describe the transverse momentum ( $p_{T}$ ) spectra of emitted particles. Our results show that the average transverse momentum ( $⟨ p_{T} ⟩$ ), the initial-state temperature ( $T_{i}$ ), and the final-state temperature ( $T_{0}$ ) roughly decrease from the lower center-of-mass energy ( $W$ ) to the higher one in the concerned energy range of a few GeV, which is different from the excitation function from heavy-ion collisions in the similar energy range.
Comments:
13 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2303.03184 [pdf]
Universe(2023)·4 citations
07
[Submitted on 6 Mar 2023]
Quasielastic (p, n) reactions described by a microscopic optical model based on the Gogny force
Juan López Moraña · Xavier Viñas
In this work we want to study quasielastic (p, n) exchange reactions using a semi-microscopic optical model derived in a previous work [1] based on a nuclear matter approach where the real and imaginary parts are given by the first and second order terms, respectively, of the mass operator obtained by a Brueckner-Hartree-Fock calculation using a G-matrix built up with an effective Gogny interaction. The study of these quasielastic reactions is performed within a Distorted Wave Born Approximation (DWBA) to evaluate the wave functions in the entrance and exit channels, which in turn are used to compute the transition matrix elements. This model, which is free of adjustable parameters, provide a reasonable good agreement with the considered experimental data, namely differential cross sections, analyzing powers and total cross sections, of different reactions spanned along the periodic table at several energies.
Comments:
15 pages 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.03206 [pdf]
J.Phys.G(2023)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Dynamical mechanisms for deuteron production at mid-rapidity in relativistic heavy-ion collisions from SIS to RHIC energies

Octupole deformation of nuclei near the spherical closed-shell configurations

Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics

Description of inclusive (d,d′x) reaction with the semiclassical distorted wave model

A Crossover phase transition based on the phenomenology of hadronic matter and quark matter

Excitation functions of related temperatures of {\eta} and {\eta}0 emission sources from squared momentum transfer spectra in high-energy collisions

Quasielastic (p, n) reactions described by a microscopic optical model based on the Gogny force

Affiliations

Description of inclusive $(d, d^{'} x)$ reaction with the semiclassical distorted wave model