Würzburg Seminar on Quantum Field Theory and Gravity

The Sachdev-Ye-Kitaev (SYK) model is a paradigm for low-dimensional holography due to its emergent reparametrization symmetry, whose spontaneous breaking governs its low-energy limit dual to AdS2 gravity. We introduce a chiral SYK chain that extends the same patterns of symmetry breaking to one dimension higher. The model's effective theory is the chiral Alekseev-Shatashvili action, a (1+1)d extension of the Schwarzian theory, that also describes low-energy fluctuations around the BTZ black hole in Einstein-Hilbert AdS3 gravity. By coupling chiralities on the boundary, we trigger a Berezinskii-Kosterlitz-Thouless (BKT)-like RG flow toward a massive phase. In the holographic bulk, this perturbation acts as a double trace deformation, leading to scalar condensation and a transition to a 'hairy' geometry. We provide a comprehensive analysis of this bulk-boundary phase structure. Based on SciPost Phys. 18, 205 (2025) and work in progress.