# Creation of momentum on vertex (quantum field theory)

For a an interaction term like $g(\overline{\psi} \gamma^\mu \psi) \partial_\mu \phi$ in which $\psi$ is a Dirac spinor and $\phi$ a scalar field (d=4), should we expect this vertex to have a momentum associated with it (from the $\partial_\mu \phi$)? If so, what is the meaning of a vertex "generating" momentum?

• The first question is closely related to Interpretation of derivative interaction term in QFT. As for the second one, who says that the vertex generates momentum? where have you read/heard this? – AccidentalFourierTransform Jan 24 '16 at 15:29
• Thanks @AccidentalFourierTransform! The interpretation interaction was really useful. I didn't read on the generating of momentum anywhere, I was just confused for the momentum term on the vertex – Sofia Jan 24 '16 at 16:12