This is more or less correct, ~1/137 corresponds to zero momentum transfer (or equivalently infinite distances). This is because of screening by particle-antip

This is more or less correct, ~1/137 corresponds to zero momentum transfer (or equivalently infinite distances). This is because of screening by particle-antiparticle pairs at larger distances. See e.g. the first few slides of http://www.fysik.su.se/~clement/teaching/emparfys/2010-2011/Lecture12.pdf http://www.fysik.su.se/~clement/teaching/emparfys/2010-2011/... (one of the first things I found in a quick search).