Action principle selection of regular black holes

Understand

We elaborate on the role of higher-derivative curvature invariants as a quantum selection mechanism of regular spacetimes in the framework of the Lorentzian path integral approach to quantum gravity.

• We show that for a large class of black hole metrics prominently regular there are higher-derivative curvature invariants which are singular.
• If such terms are included in the action, according to the finite action principle applied to a higher-derivative gravity model, not only singular spacetimes but also some of the regular ones do not seem to contribute to the path integral.