# Pion Decay and Fractional electric Charge disappeared, why?

Since the charged pions decay into two particles, a muon and a muon neutrino Fractional electric Charge disappeared, why?

The decay proceeds by the weak interaction $$W^{+}$$ and can be visualized in terms of Feynman diagrams.

my suggestion is that the Fractional electric Charge disappeared because it does not exist at all in the Quarks mechanism.

## 1 Answer

As you say, there exists a Feynman diagram

for the process, and the real question is: "what happens with the quarks"

The up and antidown quarks manage to "annihilate" into a virtual W+ which decays into the mu+ and nu_mu.

Simple. All annihilations "disappear" some quantum numbers conserving the over all quantities.

• +1: Just to make it absolutely clear to the OP, the +1/3 and +2/3 charges of the u and d(bar) add up to exactly the whole unit charge (+1) of the W+ so no charge disappears. – FrankH Sep 22 '12 at 14:09
• @anna v "what happens with the quarks", strong interaction and fractional electric charge – Neo Sep 22 '12 at 14:13
• @muster-mark In the instance you have chosen it is a weak interaction. – dmckee Sep 22 '12 at 14:35
• quarks have non zero couplings with all four interactions: strong weak electromagnetic and gravitational.The weak is the one responsible for the decays. – anna v Sep 22 '12 at 14:59