---
author:
- |
    Vincent De Comarmond$^1$, Robert de Mello Koch$^{1,2}$ and Katherine Jefferies$^{1}$\
    $^{1}$ National Institute for Theoretical Physics,\
    Department of Physics and Centre for Theoretical Physics,\
    University of the Witwatersrand,\
    Wits, 2050, South Africa\
    \
    $^{2}$Stellenbosch Institute for Advanced Studies,\
    Stellenbosch, South Africa\
    \
    E-mail:
title: Surprisingly Simple Spectra
---

Introduction
============

In the last few years interesting new progress has been made in the study of the dynamics of multimatrix models. Starting from the remarkable observation[@Corley:2001zk] that the Schur polynomials are a complete basis of gauge invariant operators which diagonalize the two point function of the free ($g_{YM}^2=0$) super Yang-Mills theory, similar bases have been found for multimatrix models[@Balasubramanian:2004nb; @de; @Mello; @Koch:2007uu; @de; @Mello; @Koch:2007uv; @Kimura:2007wy; @Bekker:2007ea; @Brown:2007xh; @Bhattacharyya:2008rb; @Brown:2008rr; @Kimura:2008wy; @Kimura:2009wy; @Ramgoolam:2008yr]. For these bases, the two point function is diagonal and known exactly as a function of $N$ (but of course, at $g_{YM}^2=0$). The fact that the $N$ dependence is known exactly suggests that these results will be useful for going beyond the planar approximation.

When would this be needed? Often “the planar limit” and “the large $N$ limit” are taken as synonyms. This is not, in general, accurate. For example, if we imagine computing 