Elementary question on Moller Scattering Feynman diagrams

by HJ Farnsworth
Tags: diagrams, elementary, feynman, moller, scattering
HJ Farnsworth
HJ Farnsworth is offline
Oct12-13, 11:03 PM
P: 108

I think this will be a very quick thread. I am new to using Feynman diagrams, and have run into something that I find puzzling. The lowest-order Coulomb interaction Feynman diagram is (image from Wikipedia Moller Scattering article):

Let's say that we are in a frame where both electrons are initially at rest. Then, it seems to me that because energy and momentum must be conserved between the beginning and end of the diagram, the two electrons must remain at rest after the interaction shown in the diagram above. So, effectively, two electons at rest near each other exchange a photon, and then nothing else happens.

But obviously, two electrons near each other will repel each other, so my question is: how does the phenomenon of two electrons at rest eventually repelling each other actually get represented via a Feynman diagram (or, alternatively, what naive mistake in my interpretation am I making)?

Thanks for any help that you can give.

-HJ Farnsworth
Phys.Org News Partner Physics news on Phys.org
Physicists consider implications of recent revelations about the universe's first light
Vacuum ultraviolet lamp of the future created in Japan
Grasp of SQUIDs dynamics facilitates eavesdropping
mfb is offline
Oct13-13, 05:20 AM
P: 10,840
Scattering descriptions don't work properly for particles at rest. The assumption that the initial and final states are without interactions fails. You can treat the system similar to bound states, see this thread for example. Solve the "classical" problem first and then calculate corrections to that.
andrien is offline
Oct13-13, 08:06 AM
P: 985
Let's say that we are in a frame where both electrons are initially at rest.
you can not find a frame in which both electron is at rest.feynman diagram is used to calculate amplitude.

Register to reply

Related Discussions
another question on Feynman diagrams High Energy, Nuclear, Particle Physics 0
Basic question about Feynman Diagrams High Energy, Nuclear, Particle Physics 7
Divergence of forward Bhabha/Moller scattering High Energy, Nuclear, Particle Physics 14
electron-electron /Moller/ Scattering Advanced Physics Homework 2
Short question: Spontaneous emission from Feynman diagrams? Quantum Physics 1