V-A sum rules with D=10 operators
  The difference of vector and axial-vector charged current correlators is analyzed by means of QCD sum rules. The contribution of 10-dimensional 4-quark condensates is calculated and its value is estimated within the framework of factorization hypothesis. It is compared to the result, obtained from operator fit of Borel sum rules in the complex q^2-plane, calculated from experimental data on hadronic tau-decays. This fit gives accurate values of the light quark condensate and quark-gluon mixed condensate. The size of the high-order operators and the convergence of operator series are discussed. 
K.N. Zyablyuk