QGLoopMomentum is an option for QGCreateAmp, which specifies the names of the loop momenta. The default value is LoopMom, which means that the loop momenta will be named LoopMom1, LoopMom2, etc.
QGLoopMomentum
QGCreateAmp
LoopMom
LoopMom1
LoopMom2
Overview, QGCreateAmp.