PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·January 30, 2025

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    Relativistic chiral nuclear forces: status and prospects

    Jun-Xu Lu🇨🇳 · Yang Xiao🇨🇳 · Zhi-Wei Liu🇨🇳 · Li-Sheng Geng🇨🇳

    Understanding nuclear structure, reactions, and the properties of neutron stars from \textit{ab initio} calculations from the nucleon degrees of freedom has always been a primary goal of nuclear physics, in which the microscopic nuclear force serves as the fundamental input. So far, the Weinberg chiral nuclear force, first proposed by the Nobel laureate Weinberg, has become the \textit{de facto} standard input for nuclear \textit{ab initio} studies. However, compared to their non-relativistic counterparts, relativistic \textit{ab initio} calculations, which describe better nuclear observables, have only begun. The lack of modern relativistic nucleon-nucleon interactions is an important issue restricting their development. In this work, we briefly review the development and status of the Weinberg chiral nuclear force, as well as its limitations. We further present a concise introduction to the relativistic chiral nuclear force, show its description of the scattering phase shifts and observables such as differential cross sections, and demonstrate its unique features. Additionally, we show that the relativistic framework could be naturally extended to the antinucleon-nucleon interaction.

    nucl-thhep-lathep-phnucl-exIJMPE(2025)·10 citations
  2. 02

    Electric dipole response of sd-shell nuclei within the Configuration-Interaction Shell Model approach

    O. Le Noan🇫🇷 · K. Sieja🇫🇷

    Reliable theoretical predictions of nuclear dipole excitations are crucial for various nuclear applications, particularly in nuclear astrophysics. Calculations of radiative capture cross sections often rely on theoretical gamma strength functions, with the electric dipole response being the dominant component. We aim at a systematic description of the E1 strength of nuclei with mass numbers between 17 and 40 of interest for various applications and to better understand the nature of the low-energy dipole strength in neutron-rich nuclei, known as pygmy dipole resonances. We use the Configuration Interaction shell-model framework in the p-sd-pf valence space with a previously established empirical Hamiltonian. Systematic results of photoabsorption strength show good agreement with experimental data, provided a renormalization of the dipole operator is applied. Transition densities are computed in 26Ne and confirm the pure isovector character of the Giant Dipole Resonance. The strength at 7-10MeV is shown to have a distinct structure with largely fragmented wave functions and transition densities of isovector character at the edge of the nucleus. The Configuration Interaction shell model is proved to be a valuable tool in the description of the photoresponse of light nuclei, providing more accurate results than the usually employed approaches.

    nucl-thPRC(2025)·6 citations
  3. 03

    Zubarev response approach to polarization phenomena in local equilibrium

    Youyu Li🇨🇳 · Shuai Y. F. Liu🇨🇳

    Using the expansion of Zubarev's density operator, we develop a linear response approach to study various spin physics in a locally equilibrated medium, particularly focusing on various polarization phenomena in heavy-ion collisions. Specifically, we connect familiar correlation functions and diagrammatic methods to the Zubarev formalism, enabling the use of established techniques like the Matsubara/imaginary time formalism to facilitate calculations. For a spin-1/2 particle, we re-derive its vector polarization using this Zubarev response approach, which exactly reproduces with our previous results based on Luttinger's method. For a spin-1 particle, we calculate the vector polarization and find the expected contributions from vorticity, temperature gradients, and shear, which are identical to those for spin-1/2 particles except for a factor of 4/3 as expected. For the tensor polarization and spin alignment of a spin-1 boson, we explicitly prove that the non-dissipative contribution is zero at leading order in gradients, and briefly reiterate our previous findings for the dissipative contribution with further discussions on several concerns. Additionally, we discuss several relevant subtleties and questions, including an alternative derivation for Zubarev response approach, the covariance issues of different spin density matrix definitions, a further explanation of slow and fast modes, the mode selection scheme, etc. We also discuss skeleton expansions, higher-order contributions, and non-perturbative methods, particularly their potential connection to lattice field theory. In summary, this work discusses the foundations and subtleties of Zubarev response approach, with specific examples from spin physics in heavy-ion collisions.

    nucl-thhep-phhep-thnucl-exPRC(2026)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE