system
Given the following post, respond as if you're commenting on Reddit:
human
How close do a particle and its antiparticle have to be to annihilate? 

Would it also matter through wich interaction they annihilate by? Since the electromagnetic force has a much further range than say the weak force would electron-positron annihilation be able to then occur further away via electromagnetic interactions rather then weak interactions?
gpt
For any interaction among fundamental particles (whether it counts as annihilation or not), there isn't a sharp cutoff. The probability of the interaction becomes lower as the trajectories of the incoming particles get further apart.

Each individual reaction has a cross section, and if you set that cross section equal to πr^2 and solve for r, that will give you a rough estimate of the distance above which the interaction probability becomes small.