  The chiral phase boundary of strong matter is determined in the T-\mu plane
from the chiral quark model, applying a non-perturbatively renormalised
treatment, involving chains of pion-bubbles and 1-loop fermion contributions.
In the absence of explicit symmetry breaking the second order portion of the
phase boundary and the location of the tricritical point (TCP) are determined
analytically. Sensitivity of the results to the renormalisation scale is
carefully investigated. The softening of the sigma-pole near the second order
transitions is confirmed.
