If a $\pi ^+ \to \nu_\mu+\mu^+$, here quark flavour is lost entirely. I am aware the weak force mediates decays where quark flavour is not conserved. But If I consider a $p+\bar p$ annihilating, here quark flavour is lost as well but the decay is not mediated by the weak force, but rather by photons (or the strong force?).
When do we use the w and z bosons in a decay?
$u \bar d$ are the quarks we start with. We end with up with 0 quarks, losing all flavour, is this still a process mediated by the weak forces W bosons? I was initially under the impression that the products still had to contain quarks for a weak force decay.