Hairy black holes in string theory

Abstract

Solutions of bosonic string theory are constructed which correspond to four-dimensional black holes with axionic quantum hair. The basic building blocks are the renormalization group flows of the ${\mathrm{CP}}^1$ model with a θ term and the SU(1,1)/U(1) WZW coset conformal field theory. However the solutions are also found to have negative energy excitations, and are accordingly expected to decay to the vacuum.