A. Zee, Quantum Field Theory in a Nutshell · Problem II.6.7

Field Theory Redux

Physics — QFT

Problem

Show that the decay rate for one boson of mass

M

into two bosons of masses

m

and

\mu

is given by

\Gamma = \frac{|\mathcal{M}|^2}{16\pi M^3}\sqrt{(M^2 - (m + \mu)^2)(M^2 - (m - \mu)^2)}