Nuclear Theory·nucl-th

Thursday·May 29, 2025

8 papers—4 primary·4 cross-listed

01
Quantum correlation dynamics and in-medium 3 $\leftrightarrow$ 3 collisions of fermions
Wolfgang Cassing
In this study we aim for quantifying the role of in-medium 3 $\leftrightarrow$ 3 collisions for systems of fermions which initially are out-off equilibrium. The formulation of the 3-body dynamics is based on the equations of motion method for identical fermions -- also denoted as quantum correlation dynamics -- and presented in detail. The on-shell 2-body collision integral is briefly reviewed and the on-shell 3-body collision integral is derived on the basis of the same two-body interaction in leading order. The resulting equations obey particle number as well as energy-momentum conservation. For a quantification of the relative impact of 3-body interactions we employ a model study for a homogeneous system in space in a finite box with periodic boundary conditions. We address spin-isospin symmetric nuclear matter systems with momentum distributions that are given by shifted Fermi spheres (without overlap) as encountered in the initial phase of nucleus-nucleus collisions after contact. The results for the relaxation times -- employing an effective 2-body interaction -- are compared to Boltzmann-Uehling-Uhlenbeck (BUU) transport calculations in the continuum limit for the same bombarding energies and are found to agree on the level of a few percent. We find that the additional 3-body interactions reduce the relaxation times up to a factor of 3 at 130 A $\cdot$ MeV. Furthermore, it is shown in BUU transport calculations that an enhanced stopping by 3 $\leftrightarrow$ 3 collisions shows up in the angular distribution of energetic nucleons ( $>$ 60 MeV) e.g. in central $_{45}^{97} R h$ collisions at 40 A $\cdot$ MeV that lead to the formation of a compound nucleus. The angular distribution of the energetic nucleons changes from a slightly forward peaked angular distribution to a slightly sidewards peaked angular distribution which might be controlled experimentally.
nucl-thPRC(2025)·1 citation
02
Constraints on the strength of first-order phase transition and its relation to nucleon mass
Bikai Gao🇯🇵
We investigate the constraints on the strength of first-order phase transitions in neutron star matter and its relation to the origin of nucleon mass. By combining the parity doublet model for the hadronic phase, the Nambu-Jona-Lasinio model for quark matter, and the integral constraint framework for intermediate densities, we construct equation of states spanning the full density range relevant to neutron stars. Our approach systematically explores how the chiral invariant mass $m_{0}$ affects the allowable properties of first-order quark-hadron phase transitions. Through comparison with recent neutron star observations, we establish a inverse correlation between the allowed phase transition strength and the chiral invariant mass. Our results demonstrate a direct connection between fundamental questions about the microscopic origin of nucleon mass and macroscopic neutron star observables, providing a novel astrophysical probe of chiral dynamics and QCD physics under extreme conditions.
nucl-th4 citations
03
Convergence of the $ppp$ correlation function within the hyperspherical adiabatic basis
E. Garrido🇪🇸 · A. Kievsky🇮🇹 · R. Del Grande🇨🇿 · L. Serksnyte🇨🇭 · M. Viviani🇮🇹 · L.E. Marcucci🇮🇹
The computation of the three-particle correlation function involving three hadrons started just recently after the first publications of ALICE measurements. Key elements to be considered are the correct description of the asymptotics, antisymmetrization issues and, in most cases, the treatment of the Coulomb interaction. In the case of the $ppp$ correlation function, a first analysis was done where the hyperspherical adiabatic method was used to determine the $ppp$ wave function at different energies. Although the asymptotic behavior, antisymmetrization issues and the treatment of the Coulomb interaction were discussed in detail, the convergence properties of the adiabatic basis were studied at low energies around the formation of the correlation peak determined mainly by the $J^{π} = 1/ 2^{-}$ and $3/ 2^{-}$ three-body states. Since many and very precise data have been taken or are planned to be measured at energies beyond the peak, we present an analysis of the convergence characteristics of the basis as the energy of the process increases. We show that in order to describe correctly the correlation tail it is necessary to consider three-body states up to $J^{π} = 21/ 2^{-}$ whereas higher states can be considered as free. Once those states are incorporated solving the associate dynamical equations, the agreement with the experimental data is found to be excellent.
nucl-thnucl-exPLB(2025)·5 citations
04
Neutron Magic Numbers in $s d$ Shell from Nuclear Charge Radii within Neutron-Proton Correction around the Fermi Surface
Yu-Ting Rong🇨🇳 · Ping-Mo Liu🇨🇳 · Dan Yang🇨🇳 · Rong An🇨🇳
Charge radii are sensitive indicators to identify the nuclear structure phenomena throughout the whole nuclide chart. In particular, the shrunken trend of changes of charge radii along a long isotopic chain is intimately associated with the shell quenching effect. In this work, the systematic evolution of charge radii along the proton numbers $Z = 8$ , $10$ , $12$ , $14$ , $18$ isotopes is investigated by a relativistic Hartree Bogoliubov model. A ansatz about neutron-proton correlation around Fermi surface is considered for describing the abnormal behavior of nuclear charge radii. Our results show that the neutron-proton pairing corrections around the Fermi surface lead to a sudden strengthening of the charge radii of these isotopic chains at $N = 8$ , 20 and 28, reflecting the fact that this correction enhances the shell closure across $N = 8$ , 20 and 28. The reproduction of the $N = 14$ charge radius in the Mg isotopes is affected by the way in which pairing correlations are handled, with BCS theory overestimating the shell effect of $N = 14$ , and the Bogoliubov quasiparticle transformation suggests a stronger pairing correlation near the proton Fermi surface, which is more consistent with experimental results. An analysis of the deviations from the theoretical and available experimental data for the charge radii of the 24 selected even-even nuclei shows that the neutron-proton pairing correction around the Fermi surface has an improved effect on the calculation of the charge {radii} using the meson-exchange effective interactions, but it does not help to significantly improve the results calculated by the density-dependent effective interactions.
nucl-thNucl.Sci.Tech.(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum correlation dynamics and in-medium 3↔3 collisions of fermions

Constraints on the strength of first-order phase transition and its relation to nucleon mass

Convergence of the ppp correlation function within the hyperspherical adiabatic basis

Neutron Magic Numbers in sd Shell from Nuclear Charge Radii within Neutron-Proton Correction around the Fermi Surface

Affiliations

Quantum correlation dynamics and in-medium 3 $\leftrightarrow$ 3 collisions of fermions

Convergence of the $ppp$ correlation function within the hyperspherical adiabatic basis

Neutron Magic Numbers in $s d$ Shell from Nuclear Charge Radii within Neutron-Proton Correction around the Fermi Surface