Yang-Mills Theories as Deformations of Massive Integrable Models

Understand

Yang Mills theory in 2+1 dimensions can be expressed as an array of coupled (1+1)-dimensional principal chiral sigma models.

• The $SU(N)\times SU(N)$ principal chiral sigma model in 1+1 dimensions is integrable, asymptotically free and has massive excitations.
• We calculate all the form factors and two-point correlation functions of the Noether current and energy-momentum tensor, in 't~Hooft's large-$N$ limit (some form factors can be found even at finite $N$).
• We use these new form factors to calculate physical quantities in (2+1)-dimensional Yang-Mills theory, generalizing previous $SU(2)$ results from Orland to $SU(N)$.