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How can I see where this formula for a general vertex factor comes from?

I have been reading Srednicki from the beginning and doing all the exercises, and I hit a big roadblock at Q10.4, as I can't seem to figure out what Srednicki is doing in his solution. Luckily, I ...
2
votes
0answers
71 views

Feynman Rules from Lagrangian with charge conjugation matrix

I'm dealing with a doubly charged scalar singlet that interacts only with the right-handed muon as follows, $$\mathcal{L} = \lambda \psi_{R}C\psi_{R} \phi^{++},$$ where $\lambda$ is the coupling, $\...
1
vote
0answers
44 views

Feynman rules for a general Lagrangian

How do I find the Feynman rules for a general Lagrangian density? For example the Lagrangian $$L = \partial_\mu \psi \partial^\mu \psi +a \psi\partial_\mu \psi \partial^\mu \psi+b \psi^2 \partial_\mu ...
1
vote
0answers
149 views

Why isn't energy conserved in time-ordered diagrams?

I'm new to particle physics, and I'm reading chapter 5 of Prof. Mark A. Thompson's "Modern Particle Physics", which talks about Time-ordered perturbation theory vs QED. However, in page 119 he wrote: ...
1
vote
0answers
482 views

$\phi^{4}$ theory Feynman rules

One of the momentum space Feynman rules in $\phi^{4}$ theory (for correlation functions) is that for an external point with 4-momentum $p$ (with direction headed towards the external point), we need a ...
1
vote
0answers
91 views

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 ...
0
votes
0answers
38 views

Feynman rules for scalar field with second order derivatives in the interaction term

Given the interaction term with $N$ scalars $\phi_i$, each massless, what would be the Feynman rules for an interaction term in the action as $$ \int d^dx (\partial^2 \phi^i)\phi_i(\partial_\mu \phi^...
0
votes
0answers
60 views

Properties of Feynman diagrams in Fermi's effective interaction theory

What are the properties of the Feynman diagrams in Fermi's effective interaction theory and how can one draw a Feynman diagram in this theory in relation to the Feynman diagram in the standard model ...
0
votes
0answers
383 views

Propagator with derivative interaction

I work with this interaction Lagrangian density $$\mathcal{L}_{int} = \mathcal{L}_{int}^{(1)} + \mathcal{L}_{int}^{(2)} + {\mathcal{L}_{int}^{(2)}}^\dagger = ia\bar{\Psi}\gamma^\mu\Psi Z_\mu +ib(\phi^...