Strange quark mass from pseudoscalar sum rule with O(αs4) accuracy

We include the new, five-loop, O(alpha(4)(s)) correction into the QCD sum rule used for the s-quark mass determination. The pseudoscalar Borel sum rule is taken as a study case. The OPE for the correlation function with (NLO)-L-4, O(alpha(4)(s)) accuracy in the perturbative part, and with dimension d <= 6 operators reveals a good convergence. We observe a significant improvement of stability of the sum rule with respect to the variation of the renormalization scale after including the O(alpha(4)(s)) correction. We obtain the interval (m) over bar (s)(2 GeV) = 105 +/- 6 +/- 7 MeV, which exhibits about 2 MeV increase of the central value, if the O(alpha(4)(s)) terms are removed.