Griffiths Introduction to Elementary Particles · Problem 2.2
Relativistic Kinematics — David J. Griffiths
Physics — QFT · feynman-diagrams
Problem
Sketch the lowest-order Feynman diagram representing Delbruck scattering: γ+γ→γ+γ. (This process, the scattering of light by light, has no analog in classical electrodynamics.)