  We study the kinetic and chemical equilibration in "infinite" parton matter
within the parton-hadron-string dynamics off-shell transport approach, which is
based on a dynamical quasiparticle model (DQPM) for partons matched to
reproduce lattice QCD results-including the partonic equation of state-in
thermodynamic equilibrium. The "infinite" parton matter is simulated by a
system of quarks and gluons within a cubic box with periodic boundary
conditions, at different energy densities, initialized slightly out of kinetic
and chemical equilibrium. We investigate the approach of the system to
equilibrium and the time scales for the equilibration of different observables.
We, furthermore, study particle distributions in the strongly interacting
quark-gluon plasma (sQGP) including partonic spectral functions, momentum
distributions, abundances of the different parton species and their
fluctuations (scaled variance, skewness, and kurtosis) in equilibrium. We also
compare the results of the microscopic calculations with the ansatz of the
DQPM. It is found that the results of the transport calculations are in
equilibrium well matched by the DQPM for quarks and antiquarks, while the gluon
spectral function shows a slightly different shape due to the explicit
interaction of partons. The time scales for the relaxation of fluctuation
observables are found to be shorter than those for the average values.
Furthermore, in the local subsystem, a strong change of the fluctuation
observables with the size of the local volume is observed. These fluctuations
no longer correspond to those of the full system and are reduced to Poissonian
distributions when the volume of the local subsystem becomes much smaller than
the total volume.
