Aspects of large N QCD phase diagrams and AdS/CFT

We will review some recent developments in understanding large N
Yang-Mills/QCD phase diagrams in various dimensions.  Parts of the
phase diagrams are calculated using standard perturbative gauge theory
techniques, sometimes with additional ingredients such as large
flavour. We will discuss two dimensional adjoint scalar QCD where the
large flavour method allows exact analytic computation of phase
boundaries which agrees with numerical calculations.  Other parts of
the phase diagrams, corresponding to strong 'tHooft coupling, are
described using AdS/CFT techniques.  We will review the conventional
holographic dual of QCD in four spacetime dimensions. We will briefly
describe a crucial problem with the conventional gravity dual of the
deconfined phase and propose a model which avoids it. The result that
chiral symmetry restoration happens at a higher temperature than the
decofinement transition is retained in our model.