What is the dominant interaction in elastic collision pi- + neutron -> pi- + neutron? Is it strong nuclear interaction or electromagnetism?
Edit: sorry I meant to say "elastic". There is no matter - energy transformation.
Elastic scattering by the optical theorem is connected to the total cross section. The total cross section is dominated by strong interaction particle creation byproducts if enough energy is available.
If the pion is very slow ( low energy)it will decay before it interacts. The nucleus coulomb barrier will be important for a small part of the phase space of increasing energy, i.e. the electron volt range. In the MeV range, where one has a chance to have a pion beam, it is the strong interaction that will take over. There will be an energy region where they are equal.