import model sm
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
define l+=e+ mu+ ta+
define l-=e- mu- ta-
generate     p p > l+ l-  j j @1
add process  p p > vl vl~ j j @2
add process  p p > l+ vl  j j @3
add process  p p > l- vl~ j j @4
output -f
