Validity of chiral perturbation theory for K0-K0 mixing
Chiral perturbation theory relates the |S|=2 matrix element K0|(sd)V-A×(sd)V-A|K0 to the |S|=1 matrix element +0|(sd)V-A(uu)V-A+(su)V- A×(ud)V-A-(sd)V-A(dd)V-A|K+. The latter matrix element is measured in K++0 decay and the former matrix element is relevant for the predictions that the standard model makes for CP nonconservation in K0-K0 mixing. In this paper the corrections of order mK4 lnmK2 to
