  Based on transport equations we argue that the chiral dynamics in heavy-ion
collisions at high collision energies effectively decouples from the thermal
physics of the fireball. With full decoupling at LHC energies the chiral
condensate relaxes to its vacuum expectation value on a much shorter time scale
than the typical evolution time of the fluid dynamical fields and their
fluctuations. In particular, the net-baryon density remains coupled to the bulk
evolution at all collision energies. As the mass scales of the hadrons are
controlled by the chiral condensate, it is reasonable to employ vacuum masses
in the statistical description of the hadron production at the chemical
freeze-out for high collision energies. We predict that at lower collision
energies the coupling of the chiral condensate to the thermal medium gradually
increases with consequences for the related hadronic masses. A new estimate for
the location of the freeze-out curve takes these effects into account.
