Study of QCD critical point with the effect of three-nucleon correlations on light nuclei yield ratios using PYTHIA8/Angantyr*

Abstract This study utilizes the PYTHIA8 Angantyr model to systematically investigate the effects of three nucleons correlation on the light nuclei yield ratio for Au+Au collisions at = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV. The analysis explores this property across different rapidity ranges, collision centralities, and collision energies, while also examining the roles of multi-parton interactions (MPI) and color reconnection (CR) mechanisms. The light nuclei yield ratio remains stable with changes in rapidity coverage and collision centrality but slightly increases with rising collision energy. The impact of CR on the light nuclei yield ratio depends on the presence of MPI; when MPI is turned off, CR has no effect. Additionally, the three-nucleon correlation enhances the light nuclei yield ratio for both central and peripheral collisions. However, the non-monotonic energy dependence observed in experiments, the peak at GeV reported by the STAR experiment, cannot be explained by the Angantyr model owing to its lack of key mechanisms related to the quark-gluon plasma (QGP). Nevertheless, the Angantyr model serves as an important baseline for studying collision behaviors in the absence of QGP effects.