FTheory: Vacuum Polarization of Subtracted Black Holes
Vacuum polarization is an important local probe of quantum fluctuations near black holes and a preliminary step for addressing the backreaction problem. For standard 4D black holes, there are analytical results only at the horizon in the static case. We study the problem for subtracted black hole geometry, a modification of the metric away from the horizon that preserves throughout the spacetime the "hidden conformal symmetry" of the near-horizon regime. In this background the Green's function has a simple explicit integral expression. We exhibit analytical results for the vacuum polarization at the horizon in both the static and the rotating case (with and without charge) and compare with existing results for standard black holes. We also discuss the prospects for extending the computation beyond the horizon.