Topological Resummation in Quantum Gravity

          @misc{ pirsa_PIRSA:25060020,
            doi = {10.48660/25060020},
            url = {https://pirsa.org/25060020},
            author = {Hernandez-Cuenca, Sergio},
            keywords = {Quantum Gravity, Quantum Information},
            language = {en},
            title = {Topological Resummation in Quantum Gravity},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {jun},
            note = {PIRSA:25060020 see, \url{https://pirsa.org}}
          }
          

Abstract

The gravitational path integral remains one of the most elusive constructs in quantum gravity, particularly in regimes dominated by topological fluctuations. In this talk, I will present recent progress in Jackiw–Teitelboim (JT) gravity, where the sum over geometries can be made precise. We demonstrate that in a low-temperature regime where semiclassical approximations fail, the all-genus thermal partition function of JT gravity admits a resummation into an effective description on a single geometry with a nonlocal deformation. This construction gives formal and geometric realization to long-standing ideas from the 1980s on wormhole-induced nonlocality, linking them to ensemble interpretations and topological expansions. The resulting theory, defined on the disk with conical defect operators, captures the complete topological expansion through an emergent nonlocal interaction, providing a precise geometric window into strongly quantum gravitational dynamics.