Estimate of the chiral condensate in quenched lattice QCD
  We determine the value of the quark condensate from quenched QCD simulations on the lattice in two ways: (i) by using the GMOR formula; (ii) by comparing the OPE prediction for the Goldstone pole contribution to the pseudoscalar vertex, at moderately large momenta. In the MSbar scheme at mu=2 GeV, from the GMOR formula we obtain <q qbar> = -(273 +/- 19 MeV)^3. We show that the value extracted from the pseudoscalar vertex, <q qbar> = - (312 +/- 24 MeV)^3, is consistent with the result obtained from the first (standard) method. 
Damir Becirevic and Vittorio Lubicz