Feynman Diagrams

Today I'm going to briefly describe the use of Feynman Diagrams to interpret interactions between sub-atomic particles.

This is a Feynman Diagram:

Looks quite complicated right?
I can assure you that once you know how they work they're pretty easy.

The diagram about shows a positron and electron collision which emits a virtual photon, this 'virtual photon' has a brief existence before splitting into a quark and an anti quark (which emits a gluon).

Now before we talk about how this works some basic knowledge of Feynman Diagrams is needed:

-Fermions (leptons and quarks) are represented by a single, black line.
-Photons are represented by a wavy line, which is often coloured blue.
-Gluons are represented by a 'loop the loop' type corkscrew line which is often coloured green.
-And Bosons are represented by a dotted line.

-Arrows point downwards for antiparticles (since time is displayed on the y axis, up, this is right)
-Time is on the y axis (up) and space is on the x axis (along), however this sometimes varies in different diagrams.
These diagrams are used to show interactions between the subatomic particles, what these interactions produced and how it is achieved. Since there is more than one way for some of these outcomes to be achieved, Feynman Diagrams can also be used to determine the probability of the outcomes.

Lets discuss another Feynman Diagram:

This diagram shows Neutron Beta Decay:

The neutron (composed of an up and two down quarks)  decays into a proton (composed of a down and two up quarks)

to get the (udd) to change into a (udu) on of the down quarks must decay into an up quark which emits a W boson,

this in turn decays into an electron anti neutrino and an electron.

In this diagram time is displayed on the y axis.

I hope this was understandable and has given you insight on Feynman Diagrams and their use, thanks for reading, Chris.