Feynman Diagram Examples

As an example we give a detailed calculation of cross section for annihilation of electron and positron into a muon pair.

Feynman diagram examples. The feynman diagram is a simple combination of a quark weak vertex and a lepton weak vertex. Examples of interactions feynman diagrams back to main physics page fundamental particles standard model exchange particles and forces the exchange of particles in an interaction can be visualised using feynman diagrams. Contents 1 natural units 2 2 single particle dirac.

In a feynman diagram the particles and the exchange particle are shown. Put a horizontal straight edge over the bottom of the diagram and move it slowly upward noticing what lines it touches. The feynman diagrams could be broken into two different orders of thinking.

A b. Examples electromagnetic p e p e qe qe m e 2 q2 strong g q q q q p s p s m p s 2 q2 weak w e d d u e u d u v ud g w g w m v udg2 w q2 m2 w dr. According to the normal view of time unrolling in one direction you start at the bottom of the diagram and read up.

Examples of feynman diagrams two electrons scattering off each other in this diagram we can see that two electrons meet exchange photons and then scatter away from each other the photon symbol γ shows that this is an example of electromagnetic interaction. You can think of these orders and the areas in between them as pyramids with different levels. Dirac equation free quantum fields and construction of feynman amplitude using feynman diagrams.

The number of ways to link an x to two external lines is 4 3 and either x could link up to either pair giving an additional factor of 2. Drawing feynman diagrams a feynman diagram is a pictorial representation of the matrix element describing particle decay or interaction a b c. The paths arrows do not represent the.

In this example the up and the antidown quarks in the pi plus annihilate to produce a w the w then materialises the lepton antilepton pair.