Quantum implementation of the cosmic censorship conjecture for toroidal black holes

We consider some aspects of quantum field theory of a conformally coupled scalar field on the singular background obtained in the massless limit of a class of toroidal black holes. The stress-tenser and its back reaction on the metric are computed using point-splitting regularization, in the cases of transparent, Neumann and Dirichlet boundary conditions. We find that the quantum fluctuations generate an event horizon which hides the singularity. The resulting object can be interpreted as a long lived remnant. We discuss the relevance of this result in the context of the cosmic censorship conjecture, and in connection to the end point of the quantum evaporation process. [S0556-2821(98)05016-4].