The second-order pion-nucleus optical potential is expressed in momentum space in terms of the off-shell matrix and the correlation function. The dependence of the matrix on the total momentum is determined within the framework of relativistic particle quantum mechanics. Numerical results are presented for scattering. It is found that the correlations tend to decrease the forward elastic cross sections by a factor of about 1.5 at low energy, MeV. At higher energies the main effect of the correlations is to increase the differential cross section at large angles. The effect of correlations on the total cross section and the pion wave function is also found to be important. A study of the dependence of the calculated cross sections on the range parameters of the matrix and of the correlations suggests that the -energy pion-nucleus scattering data cannot be adequately described by an optical model constructed from the first- and second-order terms in an expansion in terms of the matrix.
[NUCLEAR REACTIONS Second-order -nucleus optical potential studied in the multiple-scattering theory.]
- Received 18 October 1976
- Published in the issue dated July 1977
© 1977 The American Physical Society