Review of AdS/CFT Integrability, Chapter I.2: The spectrum from perturbative gauge theory

Understand

We review the constructions and tests of the dilatation operator and of the spectrum of composite operators in the flavour SU(2) subsector of N=4 SYM in the planar limit by explicit Feynman graph calculations with emphasis on analyses beyond one loop.

• From four loops on, the dilatation operator determines the spectrum only in the asymptotic regime, i.e.
• to a loop order which is strictly smaller than the number of elementary fields of the composite operators.
• We review also the calculations which take a first step beyond this limitation by including the leading wrapping corrections.