Birdtracks for SU(N)

Stefan Keppeler 

Group representations implement symmetries in quantum systems. I
review some basic notions and central results from representation
theory and sketch applications in quantum chromodynamics (QCD). The
diagrammatic birdtrack notation is a powerful tool for studying group
representations. I give a first introduction to birdtracks on familiar
ground, for vector calculus. Then we look at 6j symbols and their
applications in QCD.