AdS${}_2$ Holography and Effective QFT

We discuss AdS${}_2$ quantum gravity from an unconventional perspective that emphasizes bulk geometry. In our approach, AdS${}_2$ has no boundary, there are no divergences that require renormalization, and the dilaton of JT-gravity can be omitted altogether. The result is the standard Schwarzian theory. However, it may be advantageous that our derivation just relies on conventional AdS/CFT correspondence and effective quantum field theory. For example, it clarifies the symmetry breaking pattern. It also puts the non-compact AdS${}_2$ topology on the same footing as compact Riemann surfaces.