ELI5: Antiparticles in Feynman Diagrams

[Tulzz]

Hi!, I am studying for an introductory course in QED and Feynman Diagrams. Everything we see is like a first order approach and I am 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:
[tex]\bar{\Phi}\gamma^{\mu} \Phi A_{\mu}[/tex]
From which I understood that [tex]\bar{\Phi}[/tex] corresponds to the outgoing particle. Yet for antiparticles we draw them as entering.

Also, i don't fully understand why we use the adjoint (i.e: with [tex]\gamma^0[/tex] multiplying) as the outgoing particles. I thought we were calculating interactions elements for the Hamiltonian. I don't know where the [tex]\gamma^0[/tex] comes from.

Sorry for my english.

 

[A. Neumaier]

Feynman diagrams describe multiple integral contributing to the scattering amplitude, they don't depict events in time. (The latter is only a superficial mnemonics.) See, e.g., http://physics.stackexchange.com/a/22064/7924

The direction of the arrows comes from the direction of the momentum vector in the Fourier transform of the integrals they depict. The Fourier transform treats particle and antiparticles in a way reflecting the CTP symmetry: changing p to -p changes particles to antiparticle and reverses the signs of all charges.