2p-shell admixtures in pion single charge exchange on 13C

Abstract The pion charge exchange process 13 C (π + , π 0 ) 13 N(gs) is calculated with an extended nuclear wave function for the A=13 system that includes configurations outside the 1p-shell. A small amount of 2p-shell admixtures leads to an improved description of the experimental excitation function. We also find a strong sensitivity of the differential cross sections as well as asymmetry to contributions from higher shells.