Self-similarity of [formula omitted]-meson production in Au + Au collisions from BES-I at STAR and anomaly of “specific heat” and entropy

Abstract

We present results of analysis of KS0-meson spectra in Au+Au collisions obtained by the STAR Collaboration in the first phase of the Beam Energy Scan program at RHIC using the z-scaling approach. The analyzed data on inclusive cross sections were measured over a wide range of collision energy sNN=7.7−200 GeV and transverse momentum of produced particles for different centralities in the rapidity range |y|<0.5. A scaling behavior of the spectra in z-presentation is observed. The concept of the z-scaling is based on fundamental principles of self-similarity, locality, and fractality of hadron interactions at a constituent level. Structure of the colliding nuclei and fragmentation process in final state are described by fractal dimensions δA and ϵAA, respectively. Produced medium is characterized by a “specific heat” cAA. Onset of constant δA, smooth increase of ϵAA and anomalous behavior of cAA with collision energy in the scaling regime are observed. The self-similarity of fractal structure of nuclei and fragmentation processes with KS0 probe is demonstrated. The energy loss as a function of the collision energy, centrality and transverse momentum of the inclusive particle is estimated. An anomaly in the entropy behavior of system configurations in the region sNN∼30−40 GeV at low pT in the central collisions is found. A possible signature of phase transition indicated by the peculiarities of specific heat and entropy as ingredients of the z-scaling of KS0-meson production is discussed.