Low-temperature antihydrogen-atom scattering

A simple method to include the strong force in atom–antiatom scattering is presented. It is based on the strong-force scattering length between the nucleon and antinucleon. Using this method elastic and annihilation cross-sections are calculated for hydrogen–antihydrogen and helium–antihydrogen scattering. The results are compared to first-order perturbation theory using a pseudo-potential. The pseudo-potential approach works fairly well for hydrogen–antihydrogen scattering, but fails for helium–antihydrogen scattering where strong-force effects are more prominent.