Dynamical freeze-out phenomena: The case of $K^{\pm },\varphi$ transverse momentum spectra in collisions of Au(1.23 A GeV) + Au

Abstract

We argue on a continuous (dynamical) kinetic freeze-out of $K^{\pm },\varphi$ observed at midrapidity in collisions Au(1.23 A GeV) + Au. The simulations by means of a transport model of BUU type point to time independent transverse momentum slope parameters after 20 fm/c. The complex interplay of expansion dynamics and strangeness production/exchange/absorption as well as elastic scatterings involved in the reaction network does not support the previous interpretation of a late freeze-out of $K^{-}$ due to larger cross sections.