High Energy Theory Seminar

The Bekenstein-Hawking formula receives significant corrections for charged black holes near extremality. Using standard results in JT gravity, the correction term can semiclassically be expressed as minus the exponential of the inner horizon area, and the cancellation between outer and inner horizon areas enforces a vanishing density of states towards extremality, when the two horizons collide. Building on arXiv:2402.10162, we argue that the correction term corresponds to a complex saddle geometry of the bulk gravitational path integral. Despite violating the KSW criterion, one can describe one-loop effects on the saddle by carefully treating wrong-sign modes. Motivated by this observation, we propose a weaker version of the KSW criterion, which we call the spectral KSW criterion, and which characterizes when one-loop QFT corrections around complex gravitational saddles are well-defined. In this talk, I will emphasize the basic challenges of doing QFT on complex backgrounds, and I will explain the two perspectives (path-integral vs. spectral) which give rise to KSW and spectral KSW, respectively, using simple examples. Based on arXiv:2605.08335 with Aidan Herderschee and solo work in progress.

The talk is in 469 Lauritsen.

Contact [email protected] for Zoom information.