The Boundary Effect of s Quark Matter and Self-similarity Structure Influence of K Meson on QGP–hadron Phase Transition
Authors: Dai Ting-Ting , Cheng Luan , Ding Hui-Qiang , Zhang Wei-Ning , Wang En-Ke ,   School of Physics, Dalian University of Technology, Dalian 116024, China,   Institute of Quantum Matter, South China Normal University, Guangzhou 510631, China
Published: January 2025

We investigate the boundary effect of small-scale <inline-formula><tex-math id="M13">\begin{document}$ \text{s} $\end{document}</tex-math></inline-formula> quark matter, and the self-similarity structure influence of strange hadrons in the hadron gas on QGP–hadron phase transition. In this study, the multiple reflection expansion method is employed to investigate the boundary effect of QGP droplets containing <inline-formula><tex-math id="M14">\begin{document}$ \text{s} $\end{document}</tex-math></inline-formula> quarks. The calculation reveals that under the influence of boundary effect, small-scale <inline-formula><tex-math id="M15">\begin{document}$ \text{s} $\end{document}</tex-math></inline-formula> quark matter exhibits lower energy density, entropy density, and pressure. In hadron phase, there is the two-body self-similarity structure between <inline-formula><tex-math id="M16">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson and neighboring π mesons under the influence of collective flow, quantum correlations, and strong interactions. By applying Two-Body Fractal Model to study the self-similarity structure of the <inline-formula><tex-math id="M17">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson in meson and quark aspect, it is found that the self-similarity structure of the <inline-formula><tex-math id="M18">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson exists in hadron phase, leading to an increase in the energy density, entropy density, and pressure of the <inline-formula><tex-math id="M19">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson. With the influence of self-similarity structure, it is found that the derived transverse momentum spectrum of <inline-formula><tex-math id="M20">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson has a good agreement with experimental data (Fig. (a)). This study predicts that in the HIAF energy region, the self-similarity structure factor of <inline-formula><tex-math id="M21">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> meson <inline-formula><tex-math id="M22">\begin{document}$ q_{1} $\end{document}</tex-math></inline-formula> approaches <inline-formula><tex-math id="M23">\begin{document}$ 1.042 $\end{document}</tex-math></inline-formula>. Under the influence of boundary effect and self-similarity structure of <inline-formula><tex-math id="M24">\begin{document}$ \text{K} $\end{document}</tex-math></inline-formula> and π mesons, it shows that the phase transition temperature of <inline-formula><tex-math id="M25">\begin{document}$ \text{s} $\end{document}</tex-math></inline-formula> quark matter increases (Fig. (b)). And if the boundary of <inline-formula><tex-math id="M26">\begin{document}$ \text{s} $\end{document}</tex-math></inline-formula> quark matter curves more, the increase of phase transition temperature becomes more pronounced compared to the influence of self-similarity structure.