  The 3-D Z(3) Potts model is a model for finite temperature QCD with heavy
quarks. The chemical potential in QCD becomes an external magnetic field in the
Potts model. Following Alford et al.\cite{Alford_et_al}, we revisit this
mapping, and determine the phase diagram for an arbitrary chemical potential,
real or imaginary. Analytic continuation of the phase transition line between
real and imaginary chemical potential can be tested with precision. Our results
show that the chemical potential weakens the heavy-quark deconfinement
transition in QCD.
