Standard Model and Beyond · Problem 2.23

Lie Groups, Lie Algebras, and Symmetries

Physics — Particle Physics · electron-positron-to-pion-pair

Problem

Calculate the spin-average differential cross section

d\bar{\sigma}/d\cos\theta

in the center of mass for

e^-(p_1)e^+(p_2) \to \pi^-(p_3)\pi^+(p_4)

, and the total cross section

\bar{\sigma}

. Neglect the electron mass but not the pion mass. Ignore strong interaction effects. The angular distribution should be proportional to

\sin^2\theta

. Interpret this result.