The Quark-Gluon Mixed Condensate g<\bar{q} sigma G q> in SU(3)c Quenched   Lattice QCD
  Using the SU(3)c lattice QCD with the Kogut-Susskind fermion at the quenched level, we study the quark-gluon mixed condensate g<\bar{q} sigma G q>, which is another chiral order parameter. For each current quark mass of m_q=21, 36, 52 MeV, we generate 100 gauge configurations in the 16^4 lattice with \beta = 6.0, and perform the measurement of the mixed condensate at 16 points in each gauge configuration. Using the 1600 data for each m_q, we find the ratio between the mixed condensate and the quark condensate, m_0^2 = g<\bar{q} sigma G q>/ <\bar{q}q> \simeq 2.5 GeV^2 at the lattice scale in the chiral limit. The large value of the mixed condensate suggests its importance in the operator product expansion in QCD. 
Takumi Doi (1), Noriyoshi Ishii (2), Makoto Oka (1) and Hideo Suganuma   (1) ((1) Tokyo Inst. Tech, (2) Wako, RIKEN)