  The QCD vacuum condensates and various vacuum susceptibilities are all
important parameters which characterize the nonperturbative properties of the
QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum
susceptibilities play important roles in determining the properties of hadrons.
In this paper, we review the recent progress in studies of vacuum
susceptibilities together with their applications to the chiral phase
transition of QCD. The results of the tensor, the vector, the axial-vector, the
scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in
the framework of Dyson-Schwinger equations.
