Universality of Sparse $d>2$ Conformal Field Theory at Large $N$
  We derive necessary and sufficient conditions for large $N$ conformal field theories to have a universal free energy and an extended range of validity of the higher-dimensional Cardy formula. These constraints are much tighter than in two dimensions and must be satisfied by any conformal field theory dual to Einstein gravity. We construct and analyze symmetric product orbifold theories on $\mathbb{T}^d$ and show that they only realize the necessary phase structure and extended range of validity if the seed theory is assumed to have a universal vacuum energy. 
Alexandre Belin, Jan de Boer, Jorrit Kruthoff, Ben Michel, Edgar   Shaghoulian and Milind Shyani
hep-th