$K^{\ast }(892{)}^0$ production and the time between freeze-outs in ${}^{40}$Ar+${}^{45}$Sc collisions by NA61/SHINE at the CERN SPS

Abstract

The analysis of the production of strange $K^{\ast }(892{)}^0$ resonances allows us to better understand the temporal evolution of high-energy nucleus--nucleus collisions. In particular, the ratio of $K^{\ast }(892{)}^0$ to charged kaon yields is used to determine the time interval between chemical and kinetic freeze-outs. In this paper, the first measurements of $K^{\ast }(892{)}^0$ production in central ${}^{40}$Ar+${}^{45}$Sc collisions at the CERN Super Proton Synchrotron are reported. They were performed by NA61/SHINE at collision center-of-mass energies per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 8.8, 11.9, 16.8 GeV. The obtained $⟨K^{\ast }(892{)}^0⟩/⟨K^{+}⟩$ and $⟨K^{\ast }(892{)}^0⟩/⟨K^{-}⟩$ mean multiplicity ratios are compared with corresponding results in $p$+$p$ collisions, allowing for an estimate of the time interval between chemical and thermal freeze-outs in the ${}^{40}$Ar+${}^{45}$Sc system. These are the first such results reported for ${}^{40}$Ar+${}^{45}$Sc collisions.

12 pages, 3 figures