Elastic and charge exchange scattering of pions on 3He in the (3,3)-resonance region

The elastic scattering of pions from 3He and the single charge exchange reaction 3He(π-,π0)3H are calculated in the energy domain of the (3,3)-resonance within the framework of Glauber's theory, including spin and isospin degrees of freedom in all orders. It is pointed out that, from the first minimum on, the differential cross section strongly depends on the parametrization of the πN amplitude, especially on its continuation into the unphysical region of momentum transfer. Single and double spin flip contributions prove to be very important in the charge exchange reaction. Within a modified version of Glauber's formalism, directly using πN phase shifts rather than amplitudes, the 3He charge exchange scattering is reexamined. Whereas the shape of the angle-integrated cross section as a function of pion energy is confirmed, the magnitude is still uncertain within a factor of 2. (orig.)