Universal black hole stability in four dimensions
Abstract
We show that fourdimensional black holes become stable below a certain mass when the EinsteinHilbert action is supplemented with highercurvature terms. We prove this to be the case for an infinite family of ghostfree theories involving terms of arbitrarily high order in curvature. The new black holes, which are nonhairy generalizations of Schwarzschild's solution, present a universal thermodynamic behavior for general values of the higherorder couplings. In particular, small black holes have infinite lifetimes. When the evaporation process makes the semiclassical approximation break down (something that occurs after a time which is usually infinite for all practical purposes), the resulting object retains a huge entropy, in stark contrast with Schwarzschild's case.
 Publication:

Physical Review D
 Pub Date:
 July 2017
 DOI:
 10.1103/PhysRevD.96.024034
 arXiv:
 arXiv:1704.02967
 Bibcode:
 2017PhRvD..96b4034B
 Keywords:

 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology
 EPrint:
 12 pages, 3 figures, 2 tables