Up, anti-up quark annihilation Feynman diagram

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SUMMARY

The discussion focuses on the Feynman diagram for the annihilation process of an up quark and an anti-up quark resulting in a tau lepton pair (u ̅u → τ+τ−) at the Tevatron. The primary interaction responsible for this process is the weak force, specifically involving the exchange of W bosons. The participant identifies the challenge in visualizing the Feynman diagram due to charge conservation issues at the vertices, ruling out W bosons and gluons. The conclusion emphasizes the need to explore alternative mediators for this interaction.

PREREQUISITES
  • Understanding of Feynman diagrams
  • Knowledge of weak force interactions
  • Familiarity with particle physics terminology (e.g., quarks, leptons)
  • Basic principles of charge conservation in particle interactions
NEXT STEPS
  • Research the role of Z bosons in weak interactions
  • Study the properties of tau leptons and their decay processes
  • Explore advanced Feynman diagram techniques for complex interactions
  • Learn about charge conservation laws in particle physics
USEFUL FOR

Students and researchers in particle physics, particularly those studying weak interactions and Feynman diagrams, as well as educators preparing coursework on particle annihilation processes.

Sonko
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Homework Statement



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]

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?
 
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It can't be mediated by the W because you won't be able to conserve charge at the vertices. You can rule out gluons because they don't couple to leptons, so what else is left?
 

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