# Can an electron and a positron annihilate to form a Z_0 boson?

I guess that, since the Z boson is more massive than both the electrons, they need to go pretty fast (so that their kinetic energy is large enough), but is annihilation a property of the electromagnetic force only? Can the weak force also cause annihilation?

• @Harold: In the SM there exists a weak vertex, $e^- e ^+Z$, so you can create $Z$ bosons "directly" using the weak interaction. You can have some intermediate electromagnetic interactions but they will be higher order processes. – JeffDror Apr 26 '14 at 13:22