Griffiths Introduction to Elementary Particles · Problem 9.7

Quantum Chromodynamics — David J. Griffiths

Physics — QFT · same-flavor-quark-scattering

Problem

Show that for same-flavor quark-antiquark scattering (e.g.,

u + \bar{u} \to u + \bar{u}

), the crossed diagram does not contribute in the nonrelativistic limit.