Compton scattering in external magnetic fields: Spin-zero charged particles

Methods recently developed by Schwinger are applied to derive a general expression for the total spin-0 unpolarized Compton cross section in the presence of an arbitrarily strong homogeneous external magnetic field. This expression is correct to order {\ensuremath{\alpha}}^{2}in radiative effects, but treats the external field exactly. The motion of the incident photon is restricted to lie along the field direction. Special limiting cases...