CURRENT-CURRENT OPERATOR EVOLUTION IN THE CHIRAL LIMIT

We consider the strong interaction corrections to current-current hadr onic operators in the chiral limit. High-momentum contributions are co mputed in perturbative QCD with massless quarks while low-momentum con tributions are estimated in a truncated non-linear sigma-model for mas sless pseudoscalars. In the large-hr approximation, the ambiguity on t he momentum matching around the confining scale is removed by using th e effective color-singlet gauge boson exchanged between the two curren ts as a universal probe.