You're right, I forgot to consider \phi_1 is complex when writing down \mathcal{L} . With this in mind, writing the potentials and \mathcal{L}_{\text{I}} explicitly in \mathcal{L} gives us
\mathcal{L} = -\frac{1}{2} \eta^{\mu \nu} \partial_\mu \phi_1^* \partial_\nu \phi_1 - \frac{1}{2}...
Hi, sorry for the late reply!
As I understand it, the interaction Lagrangian tells us that there are two scalar fields \phi_1 and \phi_2 with coupling term \lambda . Lastly 2! is the symmetry factor. Since \phi_1 is charged, this field is complex (that's why we include its complex...
Hi there. I'm trying to solve the problem mentioned above, the thing is I'm truly lost and I don't know how to start solving this problem. Sorry if I don't have a concrete attempt at a solution. How do I derive the Feynman rules for this Lagrangian? What I think happens is that in momentum...