Why the HBT data are not in agreement with a single chemical and kinetic freeze-out

Abstract

Based on simple scale arguments we argue that any thermalized fireball evolution scenario which is in agreement with the observed Hanbury-Brown Twiss (HBT) correlation radii at RHIC and reproduces the measured total multiplicity cannot reflect the distribution of matter at or close to a phase transition temperature of ~170 MeV and any scenario which assumes that HBT reflects these properties cannot be reached by a sensible choice of evolution parameters while agreeing with all correlation radii. We investigate this question in more detail using a parametrized version of the fireball evolution which has been shown to reproduce particle spectra and HBT for a separate chemical and kinetic freeze-out.