Specific Heat of Nuclear Medium Probed by ${K_{S}^{0}}$ Mesons Produced in $\textrm{Au}+\textrm{Au}$ Collisions at RHIC

Abstract

The energy and centrality dependence of $K_{S}^{0}$-meson spectra measured by the STAR Collaboration at RHIC in $\textrm{Au}+\textrm{Au}$ collisions over a wide range of $\sqrt{s_{NN}}=7.7{-}200$ GeV was studied in the $z$-scaling approach. The scaling function $\psi(z)$ was constructed and the self-similarity of $K_{S}^{0}$-meson production was confirmed. This observation is consistent with an abrupt decrease of the model parameter $c_{\textrm{AuAu}}$ from the value of 0.16 at $\sqrt{s}_{NN}=7.7$ and 11.5 GeV to about 0.09 at the top RHIC energy. The scaling parameter is interpreted as a specific heat of the produced medium. The non-trivial dependence of $c_{\textrm{AuAu}}$ on the collision energy shows that $K_{S}^{0}$ meson is much more sensitive to properties of nuclear medium than a non-identified negative hadron. The irregularities in the behavior of the specific heat parameter $c_{\textrm{AuAu}}$ are considered as a possible indication of phase transition in nuclear matter.