Direct calculation of the K-matrix for pion electro-production in the delta channel

Abstract

We present a method to calculate directly the K-matrix for the pion electro-production processes in the framework of chiral quark models which allows for a clean separation of the resonant amplitudes from the background. The method is applied to the calculation of the multipole amplitudes M1+, E1+, and S1+ in the ? channel within the Cloudy Bag Model. A good overall description is found in a broad energy range.