1996/07/03 by Robbert Dijkgraaf, R. Dijkgraaf, Erik Verlinde +3 · 8 citations
Mathematics · Physics and Astronomy · #Algebraic structures and combinatorial models #Black Holes and Theoretical Physics #Degeneracy (biology) #Duality (order theory) #Dyon #Homotopy and Cohomology in Algebraic Topology #String (physics) #String theory #Type (biology) #hep-th
paper · pdf · doi:10.1016/s0550-3213(96)00640-2
published as Nucl.Phys.B484:543-561,1997 · 22 pages, latex, one epsf-figure
arxiv created 1996/07/03 · openalex publication_date 1997/01/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a microscopic index formula for the degeneracy of dyons in four-dimensional N=4 string theory. This counting formula is manifestly symmetric under the duality group, and its asymptotic growth reproduces the macroscopic Bekenstein-Hawking entropy. We give a derivation of this result in terms of the type II five-brane compactified on K3, by assuming that its fluctuations are described by a closed string theory on its world-volume. We find that the degeneracies are given in terms of the denominator of a generalized super Kac-Moody algebra. We also discuss the correspondence of this result with the counting of D-brane states.