Glauber theory and scattering off two centres

The Glauber additivity amplitude for scattering off two fixed centres is presented in a simple form for general arrangements of the centres. It is studied with respect to scattering off truncated Yukawa potentials. Scattering amplitudes are computed for three separations of the centres, corresponding to coincident, partially overlapping and non-overlapping potentials. The Glauber amplitude is compared with the impulse approximation for all separations, and with the exact solution for coincident and non-overlapping centres. It is also shown that the Glauber amplitude approximately satisfies the t-matrix unitarity condition for any arrangement of the two centres.