EFFECTS OF THE RANGE OF THE PION-NUCLEON INTERACTION ON PION-NUCLEUS SCATTERING

The range of the pion-nucleon interaction is a model-dependent quantit y, The range affects the off-shell behavior of the pion-nucleus optica l potential that is calculated from it, This will affect the different ial cross sections in turn, In this paper, we make an extensive invest igation of the effects of varying the range of the pion-nucleon intera ction on the differential cross sections of C-14 with a first-order an d a second-order optical potential. This is done for pi(+) --> pi(+), pi(+) --> pi(0) and pi(+) --> pi(-) reactions at 80, 162 and 292 MeV. It is found that varying the range of the interaction from half to twi ce its nominal value will produce large differences in the differentia l cross section including changes in the position of the first minimum , These calculations are performed in momentum space with the optical potential constructed by calculating the Fermi integral. Previous calc ulations that investigated the effect of the range of the pion-nucleon interaction on the differential cross section, were usually done with a factorized approximation, The results found here are contrary to pr evious results that agreed with the general argument that the location of the minima should be set by the location of the interaction region in the nucleus, We also investigate taking the infinite-range (zero-r ange in configuration space) limit. It is found that the differential cross sections change significantly in this limit for the charge-excha nge reactions. At 80 and 292.5 MeV it is found that the pion-nucleon P -33 channel still dominates the differential cross section.