Mixed Quark-Gluon condensate at finite temperature and density in the   global color symmetry model
  The mixed quark-gluon condensate is another chiral order parameter in QCD, which plays an important role in the application of QCD sum rules. In this letter, we study the properties of quark-gluon mixed condensate at finite temperature and quark chemical potential in the framework of global color symmetry model. Using an infrared-dominant model gluon two-point function, we find that the behavior of quark-gluon mixed condensate at finite temperature and chemical potential is similar to that of the quark condensate, and both of them give the same information about chiral phase transition. We also find that the ratio of these two condensates is insensitive to the temperature and chemical potential, which supports the conclusion obtained recently by the authors using quenched lattice QCD (They only studied the nature of the mixed quark-gluon condensate at finite temperature). 
Zhao Zhang, Wei-Qin Zhao