Exploring Pair Production: Rules and Resources

[captainhampto]

Hey all,

Just like to prefix this question with the statement that I am a computer scientist with a strong interest and passion for physics, so please forgive me if this question is a tad naive. With that out of the way, I have a general question about this image:

It's from "The Little Book of String Theory", a layman book about string theory. From what I can surmise I believe the image is describing pair production. My question is basically this:

Is there a good resource for exactly how this system is progressing? For instance the progression seems to make sense until the last slide where there appears to be a random photon in the electron/positron loop. Are these evolutionary rules consistent or dependent on certain circumstances? I suppose any resource that would elaborate on the evolutionary qualities of this process and processes like this would help out a lot. Thanks.

 

[cortiver]

These pictures are known as "Feynman diagrams". The rules for drawing them are quite simple (e.g. see http://www2.slac.stanford.edu/vvc/theory/feynman.html" which I found on Google). Understanding how they arise from quantum field theory is pretty advanced physics though.

EDIT: I should add that the diagrams you've shown don't actually represent a valid physical process. An electron can't just emit photons like that, it would violate conservation of energy in its rest frame. I guess the author just got sloppy in a book written for the general public.