  We calculate the critical exponents of the chiral phase transition at nonzero
temperature using the thermal and chiral susceptibilities. We show that within
a class of confining Dyson-Schwinger equation (DSE) models the transition is
mean field, and that an accurate determination of the critical exponents
requires extremely small values of the current-quark mass, several order of
magnitude smaller than realistic up- and down-quark masses. In general, rainbow
truncation models of QCD exhibit mean field exponents as a result of the gap
equation's fermion substructure.
