Maths HEP Lunchtime Seminars: Bifundamental Chern Simons Theories and the M/N expansion
29 May 2015 13:00 in CM221
Two very different large N expansions exist - large N vector models which contain degrees of freedom transforming in the vector representation of a gauge group and large N matrix models which contain degrees of freedom transforming in the adjoint representation of a gauge group. Large N vector models, such as the Gross Neveu model or the critical O(N) model, are exactly solvable in the 't Hooft large N limit; while their dynamics is typically very similar to free theories, or Landau liquids. Large N matrix theories, such as N=4 SYM theory or large N QCD, are not exactly solvable in the large N limit and their dynamics is now known to be potentially much more interesting, particularly at strong coupling, where there is the possibility of a dual gravity description. The M/N expansion is an expansion that takes us from large N vector saddle point to a large N matrix saddle point, and is made possible thanks to the existence of bifundamental Chern-Simons theories, unique to three dimensions. The most well-known bifundamental Chern-Simons theory is ABJM theory, but other interesting non-supersymmetric and conformal examples also exist. In this talk, which is based on work by many people over the past few years, I will discuss the landscape of bifundamental Chern-Simons theories and speculate about their possible holographic duals.