  A quark-meson-diquark plasma is considered within the PNJL model for
dynamical chiral symmetry breaking and restoration in quark matter. Based on a
generalized Beth-Uhlenbeck approach to mesons and diquarks we present the
thermodynamics of this system including the Mott dissociation of mesons and
diquarks at finite temperature. A striking result is the suppression of the
diquark abundance below the chiral restoration temperature by the coupling to
the Polyakov loop, because of their color degree of freedom. This is understood
in close analogy to the suppression of quark distributions by the same
mechanism. Mesons as color singlets are unaffected by the Polyakov-loop
suppression. At temperatures above the chiral restoration mesons and diquarks
are both suppressed due to the Mott effect, whereby the positive resonance
contribution to the pressure is largely compensated by the negative scattering
contribution in accordance with the Levinson theorem.
