Abstract:
Perhaps the simplest RG flows in the AdS/CFT correspondence are those triggered by double trace deformations. These RG flows connect two phases whose holographic duals differ by a choice of boundary asymptotics for the fluctuations of a scalar field in the unitarity window.
We consider the holographic realization of renormalization group defects separating these two CFT phases, which we call “double trace defects”. Within our setup, we compute the 2-point function at large central charge, and study its conformal block decomposition to put constraints on the spectrum of defect operators in the large N limit.
We offer two tests of our proposal. Applying our formulas to higher spin gravity in 2<d<4, we find agreement with QFT correlators for renormalization group defects in the O(N) vector model at large N.
For the second, we argue that our construction realizes within 3d higher spin gravity the renormalization group defects of the W_{N,k} minimal models studied by Gaiotto. We use our results to compute one of the bulk-boundary OPE coefficients, finding a precise match with the ’t Hooft limit of Gaiotto’s exact results.