Addendum to “Scattering of twisted particles: Extension to wave packets and orbital helicity”

In a recent work [ Phys. Rev. A 84 033804 (2011)] we considered elastic scattering of a twisted particle from a plane wave and studied how the orbital helicity of the twisted particle changes after scattering. We showed that for realistic beams the relative change can be small, |m′−m|/m≪1, thus resolving a controversy which existed in the literature. In this Addendum, using a more accurate analysis, we argue that in the kinematics of Compton backscattering a stronger statement is true: in fact m′≈m, and the difference |m′−m| even by a single unit is already suppressed.