Calculation of some properties of the vacuum
  In this article, we calculate the dressed quark propagator with the flat bottom potential in the framework of the rain-bow Schwinger-Dyson equation, which is determined by mean field approximation of the global colour model lagrangian. The dressed quark propagator exhibits a dynamical symmetry breaking phenomenon and gives a constituent quark mass about 392 MeV, which is close to the value of commonly used constituent quark mass in the chiral quark model. Then based on the dressed quark propagator, we calculate some properties of the vacuum, such as quark condensate, mixed quark condensate $g_{s}< 0|\bar{q}G_{\mu\nu}\sigma^{\mu\nu}q|0>$, four quark condensate $<0|\bar{q} \Gamma q\bar{q} \Gamma q |0>$, tensor, $\pi$ vacuum susceptibilities. The numerical results are compatible with the values of other theoretical approaches. 
Z.G.Wang (IHEP)