Define the model:

model = SM

Define containers for electrons and muons (and photons):

alias lep = e1:E1:e2:E2
alias prt = lep:A

The Born process and and additional bremsstrahlung photon, compilation:

process born = e1, E1 => e2, E2
process rc = e1, E1 => e2, E2, A
compile