Finite energy chiral sum rules in QCD

The saturation of QCD chiral sum rules of the Weinberg-type is analyzed using ALEPH and OPAL experimental data on the difference between vector and axial-vector correlators (V-A). The sum rules exhibit poor saturation up to current energies below the tau-lepton mass. A remarkable improvement is achieved by introducing integral kernels that vanish at the upper limit of integration. The method is used to determine the value of the finite remainder of the V-A correlator, and its first derivative, at zero momentum: Π-bar(0)=-4L-bar10=0.0257±0.0003, and Π-bar'(0)=0.065±0.007 GeV-2. The dimension d=6 and d=8 vacuum condensates in the operator product expansion are also determined: =-(0.004±0.001) GeV6, and =-(0.001±0.006) GeV8