K-0 form factor at order p(6) of chiral perturbation theory

This paper describes the calculation of the electromagnetic farm factor of the K-0 meson at order p(6) of chiral perturbation theory which is the next -to-leading order correction to the well-known p(4) result achieved by Gass er and Leutwyler. On the one hand, at order p(6) the chiral expansion conta ins 1- and 2-loop diagrams which are discussed in detail. Especially, a num erical procedure for calculating the irreducible 2-loop graphs of the sunse t topology is presented. On the other hand, the chiral Lagrangian L-(6) pro duces a direct coupling of the K-0 current with the electromagnetic field t enser. Due to this coupling one of the unknown parameters of L-(6) occurs i n the contribution to the K-0 charge radius. (C) 2001 Elsevier Science B.V. All rights reserved.