Griffiths Introduction to Elementary Particles · Problem 7.24

Electrodynamics of Quarks and Hadrons — David J. Griffiths

Physics — QFT · electron-muon-scattering-amplitude

Problem

Evaluate the amplitude for electron-muon scattering (7.104) in the

CM

system, assuming the

e

and

\mu

approach one another along the

z

axis, repel, and return back along the

z

axis. Assume the initial and final particles all have helicity

+1

. [Answer:

\mathcal{M} = -2g_e^2

]