Explicit inclusion of spin-orbit contribution in THSR wave function

TL;DR

This paper enhances the THSR wave function by explicitly including spin-orbit effects using AQCM, improving the modeling of alpha clustering in nuclei like 12C.

Contribution

It introduces a method to incorporate spin-orbit contributions into the THSR wave function, combining it with AQCM for more accurate nuclear structure modeling.

Findings

Spin-orbit effects are significant at short alpha-alpha distances.

Monte Carlo integration effectively computes the multi-dimensional integrals.

The modified wave function better reproduces nuclear properties.

Abstract

The Tohsaki-Horiuchi-Schuck-Roepke (THSR) wave function has been successfully used for the studies of gas-like nature of alpha clusters in various nuclei including the so-called Hoyle state of 12C and four alpha states of 16O. In standard alpha cluster models, however, each alpha cluster wave function has spin zero because of its spatial symmetry and antisymmetrization effect. Thus the non-central interactions do not contribute, and this situation is the same in the THSR wave function. In this work, the spin-orbit contribution, which is found to be quite important at short alpha-alpha distances, is taken into account in the THSR wave function by combing it with antisymmetrized quasi cluster model (AQCM). The application to 12C is presented. The multi-integration in the original THSR wave function is carried out by using Monte Carlo technique, which is called Monte Carlo THSR wave function. For the nucleon-nucleon interaction, the Tohsaki interaction, which contains finite-range three-body terms and simultaneously reproduces the saturation properties of nuclear systems, the alpha-alpha scattering phase shift, and the size and binding energy of 4He, is adopted.