We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio model at finite temperature and non-zero chemical
potential with three quark flavors. Chiral and deconfinement phase transitions
are discussed and the relevant order-like parameters are analyzed. The results
are compared with simple thermodynamic expectations and lattice data. We
present the phase diagram in the (T,μB) plane, paying special attention
to the critical end point: as the strength of the flavor-mixing interaction
becomes weaker, the critical end point moves to low temperatures and can even
disappear.Comment: 46 pages, 11 figures, 3 table