# ELI5: Antiparticles in Feynman Diagrams

1. Nov 16, 2015

### Tulzz

Hi!, Im studying for an introductory course in QED and Feynman Diagrams. Everything we see is like a first order approach and im having some trouble understanding antiparticles in Feynman Diagrams:
Why is it that we put an antiparticle that is leaving as if it is entering the interaction??
This is:
We have the interaction term:
$$\bar{\Phi}\gamma^{\mu} \Phi A_{\mu}$$
From which I understood that $$\bar{\Phi}$$ corresponds to the outgoing particle. Yet for antiparticles we draw them as entering.

Also, i dont fully understand why we use the adjoint (i.e: with $$\gamma^0$$ multiplying) as the outgoing particles. I thought we were calculating interactions elements for the Hamiltonian. I dont know where the $$\gamma^0$$ comes from.

Sorry for my english.

Last edited: Nov 16, 2015
2. Nov 21, 2015