A formula for Wilson loop expectations in 2d Yang–Mills theory
By Thierry Lévy
Wilson loops are the basic observables of Yang—Mills theory, and their expectation is rigorously defined on the Euclidean plane and on a compact Riemannian surface. Focusing on the case where the structure group is the unitary group, I will present a formula that computes any Wilson loop expectation in almost purely combinatorial terms, thanks to the dictionary between unitary and symmetric quantities provided by the Schur-Weyl duality.