Microscopic description of D-brane black holes

Abstract

We discuss the derivation of the effective SCFT description of certain aspects of the near extremal 5-dimensional black hole, which is modelled by a collection of D1- and D5-branes, by studying the corresponding U(Q₁) × U(Q₅) gauge theory in 2-dimensions. We give an analysis of the Higgs branch moduli to extract the independent degrees of freedom in a unitary gauge and then indicate the relevance of the residual S(Q₁) × S(Q₅) Weyl invariance to extract the low-energy degrees of freedom. These are strings corresponding to the maximal cycle of the Weyl subgroup. The corresponding sigma model in terms of these strings is non-linear and non-local. We calculate the string tension. Assuming that long wavelength fluctuations are governed by a local SCFT with N=4 SUSY, we indicate how, under mild assumptions, the sigma model becomes a free SCFT with an internal symmetry group SO(4) and central charge c = 6. We also discuss the coupling of the SCFT to bulk matter. Our considerations imply that the calculation of the Hawking decay rate has a sound foundation in string theory and is valid in the black hole regime where g^{N ~} 1.