Diverging black hole entropy from quantum infrared non-localities

TL;DR

This paper demonstrates that certain infrared non-localities in quantum effective actions can cause black hole entropy to diverge, challenging the thermodynamic stability of large black holes and constraining the form of quantum corrections.

Contribution

It reveals how infrared non-localities in quantum gravity lead to diverging black hole entropy, providing new constraints on effective action form factors.

Findings

Large black hole entropy can diverge due to infrared non-localities.

Divergences imply black holes are either highly chaotic or thermodynamically unstable.

Constraints are derived on the form factors in the quantum effective action.

Abstract

Local higher-derivative corrections to the Einstein-Hilbert action yield sub-leading corrections to the Bekenstein-Hawking area law. Here we show that if the quantum effective action comprises a certain class of infrared non-localities, the entropy of large black holes generally diverges to either positive or negative infinity. In such theories, large spherically symmetric black holes would be either highly chaotic or thermodynamically impossible, respectively. In turn, this puts strong constraints on the Laurent expansion of the form factors in the effective action.