2002/11/30 by O. B. Zaslavskii, О. Б. Заславский
Physics and Astronomy · #Black Holes and Theoretical Physics #Black hole (networking) #Classical mechanics #Cosmology and Gravitation Theories #Degenerate energy levels #Dilaton #Gravitation #Mathematical physics #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum gravity #Quantum mechanics #Semiclassical physics #Spacetime #Theoretical physics #gr-qc #hep-th
paper · pdf · doi:10.1088/0264-9381/20/1/311
published as Class.Quant.Grav. 20 (2003) 137-154 · 31 pages. In v.2 typo in Ref. [2] corrected, 4 references added. Accepted in Class. Quant. Grav
arxiv created 2002/12/05 · openalex publication_date 2002/12/13 · arxiv updated 2017/08/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Previously known exactly solvable models of 2D semiclassical dilaton gravity admit, in the general case, only non-extreme black holes. It is shown that there exist exceptional degenerate cases that can be obtained by some limiting transitions from the general exact solution, which include, in particular, extremal and ultraextremal black holes. We also analyse properties of extreme black holes without demanding exact solvability, and show that for such solutions quantum backreaction forbids the existence of ultraextreme black holes. The conditions under which divergencies of quantum stresses in a free-falling frame can disappear are found. We derive the closed equation with respect to the metric as a function of the dilaton field that enables one, choosing the form of the metric, to restore corresponding Lagrangian. It is demonstrated that exactly solvable models, found earlier, can be extended to include an electric charge only in two cases: either the dilaton–gravitation coupling is proportional to the potential term, or the latter vanishes. The second case leads to the effective potential with a negative amplitude and we analyse how this fact affects the structure of spacetime. We also discuss the role of quantum backreaction in the relationship between extremal horizons and the branch of solutions with a constant dilaton.