F-theory and AdS_3/CFT_2 (2,0)

We continue to develop the program initiated in arXiv:1705.04679 of studying supersymmetric AdS_3 solutions of F-theory and their holographic dual 2d superconformal field theories, which are dimensional reductions of 4d theories with varying coupling. Imposing 2d N=(0,2) supersymmetry, we derive the general conditions on the geometry for Type IIB AdS_3 solutions with varying axio-dilaton and five-form flux. We discuss a class of solutions, which extend AdS_3 x T^2 x M_5 Type IIB backgrounds, to F-theory geometries of the type AdS_3 x K3 x M_5 with varying axio-dilaton characterizing the elliptic fiber of the K3, and describe their dual field theories. For a specific choice of M_5 this corresponds to a family of solutions that are conjectured to be dual to twisted compactifications of 4d N=1 Y^{p,q} quiver gauge theories on a curve with varying coupling. For this setup, we compare the central charges from holography and field theory and find agreement to subleading order in N. Requiring enhanced 2d N=(2,2) supersymmetry we find that the axio-dilaton must be constant. However, if the internal geometry is allowed to be non-compact, we obtain the most general class of Type IIB AdS_5 solutions with varying axio-dilaton, i.e. F-theoretic solutions, that are dual to 4d N=1 SCFTs.