Defects in 4d SCFTs from supergravity and holographic renormalization
摘要
Type IIB string theory admits Janus solutions connecting AdS5 vacua. These geometries correspond to interface conformal field theories and are naturally described in five-dimensional supergravity as AdS4 foliations over an interval. In this work, we introduce a novel type of Janus solution in AdS5, featuring AdS2 × S2 foliations instead of AdS4. We interpret these solutions as the supergravity duals of line defects in four-dimensional SCFTs and we discuss their D-brane engineering. Our primary tool is Romans supergravity in five dimensions, which provides a simple Type IIB truncation over S5. Within this framework, under specific conditions, we construct regular solutions interpolating between AdS5 and AdS2 × ℝ3. These geometries represent one-parameter deformations of AdS5 vacua and are characterized by a running profile for two-form gauge potentials and a scalar field in the supergravity bulk. Finally, using holographic renormalization, we explicitly compute the on-shell action of the defect and we discuss the one-point functions in the holographic field theory.