Differential cross sections for the pion double-charge-exchange reaction Ca42(+,-)Ti42(g.s.) have been measured at lab=5°at several energies. For T(+)<200 MeV, (5°) are found to be more than an order of magnitude larger than those predicted by conventional double-charge-exchange calculations. It is shown that the observed enhancements can be explained in terms of coherent contributions due to terms proportional to 2(r) in the pion-nucleus potential whose importance is dramatically enhanced in the presence of large core-excitation components in Ca42(g.s.).
ASJC Scopus subject areas
- Physics and Astronomy(all)