Griffiths Introduction to Elementary Particles · Problem 3.23

Symmetries — David J. Griffiths

Physics — QFT · mandelstam-variables-identical-particles

Problem

For elastic scattering of identical particles,

A + A \to A + A

, show that the Mandelstam variables (Problem 3.22) become

\begin{aligned} s &= 4(p^2 + m^2c^2)/c^2\\ t &= -2p^2(1 - \cos\theta)/c^2\\ u &= -2p^2(1 + \cos\theta)/c^2 \end{aligned}

where

\mathbf{p}

is the CM momentum of the incident particle, and

\theta

is the scattering angle.