Feynman diagram symbols
Feynman diagrams are intended to help us to think about about what happens in sub atomic interactions. They cannot represent anything like a true image of interactions because they take place in three dimensions in space and also in time.
We use a code on the diagrams, you might find different codes used by some publishers. This code is used by the Institute of Physics and is common, but not universal.
Feynman diagrams
The particles entering and leaving the interaction (fermions) are shown as solid lines. Exchange particles shown here are either photons or weak interaction bosons.
Changes in direction of the particles represent a change in momentum but they are not vector diagrams, there is no scale. An upward arrow on the line shows a real particle and a downward arrow is an antiparticle. Most diagrams have time on the Y axis but often the X axis is not labelled.
For example, interaction between two electrons.
The wavy line represents the energy change
or exchange particle which has a
brief or virtual existence.
In this case a photon
More examples
