Abstract
We point out that two-dimensional Russo-Susskind-Thorlacius (RST) model for evaporating black holes is locally equivalent — at the full quantum level — to flat-space Jackiw-Teitelboim (JT) gravity that was recently shown to be unitary. Globally, the two models differ by a reflective spacetime boundary added in the RST model. Treating the boundary as a local and covariant deformation of quantum JT theory, we develop sensible semiclassical description of evaporating RST black holes. Nevertheless, our semiclassical solutions fail to resolve the information recovery problem, and they do not indicate formation of remnants. This means that either the standard semiclassical method incorrectly describes the evaporation process or the RST boundary makes the flat-space JT model fundamentally inconsistent.
Highlights
One promotes the one-loop RST model to a full quantum theory: one adds RST counter-term [19] and N matter fields fi(x) to the action of dilaton gravity [20], and quantizes the resulting theory in a consistent way suggested by Strominger [21]
Works observed [19, 23,24,25] that the semiclassical solutions describing evaporating RST black holes develop curvature singularities at φ = φcr, and this impedes quantization of the theory [26]
We find that the spacetime of evaporating black hole can be continued into the future beyond the last ray S L
Summary
Two-dimensional Russo-Susskind-Thorlacius (RST) model [19] describes interaction of N matter fields fj(x) with non-dynamical gravitational sector: metric gμν(x) and dilaton φ(x). The problem is that the Hawking flux from these objects is always proportional [20] to the factor in front of the one-loop action (2.4) — the total central charge c = N − 24 The latter, receives contributions from the entire field content of the model: N from matter fields, +2 from non-dynamical fields φ and ρ, and −26 from ghosts. In what follows we will strongly rely on the fact [4, 5] that the flat-space JT gravity is a healthy quantum theory with unitary S-matrix This implies, in particular, that the RST model remains local and diffeomorphism-invariant after distortion of the functional measures performed in (2.5). Gives path integral with canonical functional measures and new local counter-terms in the action
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