Pion-deuteron scattering sensitivity to the nucleon-nucleon hard core

We calculate pion-deuteron elastic scattering at 142, 181, and 254 MeV, using four separable models of the off-shell nucleon-nucleon T matrix. The form factors for two of these models were obtained by fitting the low-energy data, as well as the change of sign of the phase shifts at Tlab300 MeV, by means of energy-dependent separable potentials. These form factors have ranges in momentum space which are larger than those of the Yamaguchi potentials. We find that the differential cross section for pion-deuteron scattering is very sensitive to the off-shell behavior of the nucleon-nucleon T matrix. We also find that it is possible to fit the data at 254 MeV by using the long-range form factors that take into account the hard core, although the data at 142 MeV is better described using shorter ranges. NUCLEAR REACTIONS d()d, E=142, 181, 254 MeV; calculated dd.