  We study the particle production in the early stage of the ultrarelativistic
heavy-ion collisions. To this end the Boltzmann kinetic equations for gluons
and pions with elastic rescattering are considered together with a simple model
for the parton-hadron conversion process (hadronisation). It is shown that the
overpopulation of the gluon phase space in the initial state leads to an
intermediate stage of Bose enhancement in the low-momentum gluon sector which
due to the gluon-pion conversion process is then reflected in the final
distribution function of pions. This pattern is very similar to the
experimental finding of a low-momentum pion enhancement in the ALICE experiment
at CERN LHC. Relations to the thermal statistical model of hadron production
and the phenomenon of thermal and chemical freeze-out are discussed in this
context.
