Multi-trace correlators from permutations as moduli space

Abstract

We study the n-point functions of scalar multi-trace operators in the U(Nc) gauge theory with adjacent scalars, such as mathcal{N} = 4 super Yang-Mills, at tree-level by using finite group methods. We derive a set of formulae of the general n-point functions, valid for general n and to all orders of 1/Nc. In one formula, the sum over Feynman graphs becomes a topological partition function on Σ0,n with a discrete gauge group, which resembles closed string interactions. In another formula, a new skeleton reduction of Feynman graphs generates connected ribbon graphs, which resembles open string interaction. We define the moduli space {mathrm{mathcal{M}}}_{g,n}^{mathrm{gauge}} from the space of skeleton-reduced graphs in the connected n-point function of gauge theory. This moduli space is a proper subset of {mathrm{mathcal{M}}}_{g,n} stratified by the genus, and its top component gives a simple triangulation of Σg,n.