Two-point function of strangeness-carrying vector currents in two-loop chiral perturbation theory

We calculate the correlator between two external vector currents having the quantum numbers of a charged kaon. We give the renormalized expression to two loops in standard chiral perturbation theory in the isospin limit, which, as a physical result, is finite and scale independent. Applications include a low energy theorem, valid at two loop order, of a flavor breaking combination of vector current correlators, as well as a determination of the phenomenologically relevant finite O(p6)-counterterm combination QV by means of inverse moment finite energy sum rules. This determination is less sensitive to isospin-breaking effects than previous attempts. (c) 2000 The American Physical Society