Gauges, propagators, and physics

Understand

When a theory shall be described at all scales, it is necessary to start from its elementary degrees of freedom.

• Herein, one possible chain of steps for this purpose will be briefly outlined for the example of a gauge theory, like QCD.
• Starting with the elementary constituents, gluons and quarks, step by step the final observables, physical states, will be built up.
• This process is based on the elementary correlation functions, and uses a combination of both numerical lattice calculations and functional continuum methods.