1. The problem statement, all variables and given/known data At the Tevatron you observe the process u ̅u → τ+τ−. Draw the lowest order Feynman diagrams for the processes involved and state which interactions are responsible. Label all internal lines, external lines and vertices [u = up quark, τ = tau lepton] 3. The attempt at a solution Once i have the basic feynman diagram i can eaily label the internal/external lines and the vertices, however i'm simply having a problem identifying the diagram. From what i can think of right now i would assume the weak force (W-) is the process involved which would be just like a time reversed tau decay, however i can't picture how the feyman diagram would look?