I was looking at the potential of interaction of an electron and a positron in a Feynman's diagram, if one side is negative and the other is positive there is an attractive force between the two particles, ok simple math I think I got it! Now how does this intrinsic property allows the particle to pull and push another particle and where does the conservation of momentum kicks in? I believe momentum is conserved when the forces you applied to the particle becomes friction and transfer a portion to the other particle but how is it connected to quantum spin?
For clarification: picture 2 electrons already repelling each other at a distance, if I apply a force to push 1 of them closer to the other then by virtue of conservation of momentum the other electron must accelerate in opposite direction. But this is not related to how quantum spins allow particle to be able to push and pull each other in the first place!
