Quark chiral condensate from the overlap quark propagator
  From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with $N_f=2+1$ flavors. Three ensembles with different light sea quark masses are used at one lattice spacing $1/a=1.75(4)$ GeV. We obtain $\langle\bar\psi\psi\rangle^{\overline{\rm MS}}(2\mbox{ GeV})=(-305(15)(21)\mbox{ MeV})^3$ in the SU(2) chiral limit. 
Chao Wang, Yujiang Bi, Hao Cai, Ying Chen, Ming Gong and Zhaofeng Liu
hep-lat hep-ph