Strings on a cone and black hole entropy

Abstract

String propagation on a cone with deficit angle 2π (1 - 1/N) is described by constructing a non-compact orbifold of a plane by a Z_N subgroup of rotations. It is modular invariant and has tachyons in the twisted sectors that are localized at the tip of the cone. A possible connection with the quantum corrections to the black hole entropy is outlined. The entropy computed by analytically continuing in N would receive contribution only from the twisted sectors and be naturally proportional to the area of the event horizon. Evidence is presented for a new duality for these orbifolds similar to the R →1/R duality.