  The thermodynamics of QCD with sufficiently heavy dynamical quarks can be
described by a three-dimensional Polyakov loop effective theory, obtained after
a truncated character and hopping expansion. We investigate the resulting phase
diagram for low temperatures by mean field methods. Taking into account
chemical potentials for both baryon number and isospin, we obtain clear signals
for a liquid-gas type transition to baryon matter at $\mu_I=0$ and a
Bose-Einstein condensation transition at $\mu_B=0$, as well as for their
connection when both chemical potentials are non-zero.
