  Sufficiently fast chemical equilibration of (strange) antibaryons in an
environment of nucleons, pions and kaons during the course of a relativistic
heavy ion collision can be understood by a `clustering' of mesons to build up
baryon-antibaryon pairs. This multi-mesonic (fusion-type) process has to exist
in medium due to the principle of detailed balance. Novel numerical
calculations for a dynamical setup are presented. They show that - at maximum
SPS energies - yields of each antihyperon specie are obtained which are
consistent with chemical saturated populations of T approximately 150-160 MeV,
in line with popular chemical freeze-out parameters extracted from thermal
model analyses.
