  In this paper, we suggest a method of a complete calculation of the
Sommerfeld effect in both the s-wave and p-wave annihilation situations. The
basic idea is to uniformly consider the equal-time Beth-Salpeter wave functions
of both the dark matter and the final state particles, then short-distance
interactions can be parametrized as a cross-term considering the equations.
Solving these equations will result in the complete formulas of the cross
sections with the Sommerfeld effects.
