Mixed tensor susceptibility of the QCD vacuum from effective quark-quark   interactions
  We calculate the mixed tensor susceptibility of QCD vacuum in the framework of the global color symmetry model. In our calculation, the functional integration over gluon fields can be performed and the gluonic vacuum observable can be expressed in terms of the quark operators and the gluon propagator. The mixed tensor susceptibility was obtained with the subtraction of the perturbative contribution which is evaluated by the Wigner solution of the quark gap equation. Using several different effective quark-quark interaction models, we find the values of the mixed tensor susceptibility are very small. 
Zhao Zhang, Wei-qin Zhao