Anti-de Sitter fragmentation. (English) Zbl 0956.83052

Summary: Low-energy, near-horizon scaling limits of black holes which lead to string theory on \(\text{AdS}_2 \times S^2\) are described. Unlike the higher-dimensional cases, in the simplest approach all finite-energy excitations of \(\text{AdS}_2 \times S^2\) are suppressed. Surviving zero-energy configurations are described. These can include tree-like structures in which the \(\text{AdS}_2 \times S^2\) throat branches as the horizon is approached, as well as disconnected \(\text{AdS}_2 \times S^2\) universes. In principle, the black hole entropy counts the quantum ground states on the moduli space of such configurations. In a nonsupersymmetric context \(\text{AdS}_D\) for general \(D\) can be unstable against instanton-mediated fragmentation into disconnected universes. Several examples are given.


83E30 String and superstring theories in gravitational theory
83C57 Black holes
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