  QCD thermodynamics is studied using a model which combines Polyakov loop
dynamics with spontaneous chiral symmetry breaking and its restoration (the
PNJL model). The input is fixed entirely by pure-gauge lattice QCD results and
by pion properties in vacuum. Successful comparisons with results from thermal
lattice QCD are achieved, including extrapolations to finite quark chemical
potential. The phase diagram and selected susceptibilities for two quark
flavors are investigated with inclusion of diquark degrees of freedom.
