Griffiths Introduction to Elementary Particles · Problem 9.11

Quantum Chromodynamics — David J. Griffiths

Physics — QFT · three-gluon-diagram-contribution

Problem

Confirm that diagram 3 (the three-gluon vertex diagram) makes no contribution to

q + \bar{q} \to g + g

when the quarks are at rest in the spin singlet configuration, by showing that all terms in

\mathcal{M}_3

are proportional to

\epsilon_3 \cdot \epsilon_4