PaperPanorama

Nuclear Theory·nucl-th

Monday·January 22, 2024

9 papers5 primary·4 cross-listed

  1. 01

    Barrier penetration in a discrete-basis formalism

    G.F. Bertsch · K. Hagino

    The dynamics of a many-particle system are often modeled by mapping the Hamiltonian onto a Schrödinger equation. An alternative approach is to solve the Hamiltonian equations directly in a model space of many-body configurations. In a previous paper the numerical convergence of the two approaches was compared with a simplified treatment of the Hamiltonian representation. Here we extend the comparison to the nonorthogonal model spaces that would be obtained by the generator-coordinate method. With a suitable choice of the collective-variable grid, a configuration-interaction Hamiltonian can reproduce the Schrödinger dynamics very well. However, the method as implemented here requires that the barrier height is not much larger than the zero-point energy in the collective coordinates of the configurations.

    nucl-thPRC(2024)·6 citations
  2. 02

    Photoproduction of lepton pair in ultra-relativistic heavy-ion collisions

    Kewei Yu🇨🇳 · Jiazhen Peng🇨🇳 · Shuang Li🇨🇳 · Kejun Wu🇨🇳 · Wei Xie🇨🇳 · Fei Sun🇨🇳

    Dilepton production provides a unique probe of the strong electromagnetic field produced in heavy-ion collisions. To map out the behavior of its transverse momentum broadening, we present a theoretical model based on the equivalent photon approximation, and then we update it to make direct comparisons with the recent experimental measurements. We find that the model calculations can describe well, not only the average transverse momentum squared of pairs in Au--Au collisions at GeV, but also the acoplanarity of pairs in Pb--Pb collisions at TeV. Furthermore, the model predictions are also able to reproduce the measured dependencies of the pair mass and the transverse momentum squared.

    nucl-thhep-phPRC(2024)·3 citations
  3. 03

    Fine-tuning of the quasi-bound state

    N.V. Shevchenko🇨🇿

    Characteristics of the quasi-bound state in the system strongly depend on the model of antikaon-nucleon interaction and weakly - on the nucleon-nucleon potential. In the present paper, dynamically exact Faddeev-type calculations with coupled and were performed using different models of the and interactions to study the influence of these "less important" interaction on the three-body result. In addition, dynamically exact three-body Faddeev-type AGS calculations with three coupled particle channels were performed.

    nucl-thFew Body Syst.(2024)·1 citation
  4. 04

    Neutrino-Neutron Scattering Opacities in Supernova Matter

    Gang Guo🇨🇳 · Gabriel Martínez-Pinedo🇩🇪 · Meng-Ru Wu🇹🇼

    We compute the static density and spin structure factors in the long wavelength limit for pure neutron matter at subsaturation densities relevant to core-collapse supernovae within the Brueckner-Hartree-Fock (BHF) approach. The BHF results are reliable at high densities, extending beyond the validity of the virial expansion. Motivated by the similarities between the dilute neutron gas and a unitary gas, we propose a phenomenological approach to derive the static structures with finite momentum transfer as well as the dynamic ones with simple analytical expressions, based on the computed static structures in the long wavelength limit. We also compare the in-medium neutrino-neutron scattering cross sections using different structure factors. Our study emphasizes the importance of accurately computing the static structure factors theoretically and utilizing the full dynamic structure factors in core-collapse supernova simulations.

    nucl-thastro-ph.SRPRC(2024)·2 citations
  5. 05

    Unified neutron star equations of state calibrated to nuclear properties

    Tuhin Malik🇵🇹 · Helena Pais🇵🇹 · Constança Providência🇵🇹

    Recently, in Malik23, a dataset of several EoS for purely nucleonic stellar matter based on a non-linear RMF model prescription, and constrained to properties of nuclear matter, to state-of-the-art chiral effective field theory calculations for low-density neutron matter, and to astrophysical data, were proposed. In this work, twenty one unified neutron star EoS were chosen from that dataset, in such a way that a large range of values of the slope of the symmetry energy at saturation is covered. Several quantities are calculated and discussed, such as the the proton fraction and the direct Urca behavior, the density dependence of the speed of sound and the trace anomaly, the crust-core transition properties, the compatibility with astrophysical observations, and the neutron matter properties from EFT calculations and pQCD constraints. We construct unified EoS, where the outer crust is given by the BSk22 functional, and the inner crust is calculated from a CLD approximation. The core is purely nucleonic, made of protons, neutrons, electrons and muons, under charge neutrality and in equilibrium conditions. The correlation of the slope of the symmetry energy at saturation with the crust-core transition density and proton fraction is analysed, and equations that translate these relations are proposed. Moreover, the spectral representation for all the EOS according to the format proposed in Lindblom10 is given, which is a convenient representation to study quasi-periodic oscillations with realistic EOS. It is shown that several of these EoS have in the center of the most massive NS a speed of sound squared of the order of . Most of the EoS predict a maximum central density of the order of about 6 times the nuclear saturation density. Three of the EoS satisfy all of the constraints imposed. All these EoS will be made available in the CompOSE platform.

    nucl-thAstron.Astrophys.(2024)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE