The neutral pion decays 99 percent of the time by the reaction 0 2. The

The neutral pion decays 99 percent of the time by the reaction π⁰ → 2ϒ. The π^- decays by the reaction π^- → μ^- + v̅_μ.

(a) Assuming the π⁰ to consist of a uu̅ quark pair, show how the 2ϒ occurs. 

(b) Why is a π⁰ decay to a single photon not possible? 

(c) The π^- is a u̅d quark combination. Draw a Feynman diagram for the π^- decay.