Two Centered Black Holes and N=4 Dyon Spectrum

TL;DR

This paper explains how the discontinuous changes in dyon spectrum in N=4 string theories across walls of marginal stability are precisely accounted for by the entropy of two centered small black holes that vanish when crossing these walls.

Contribution

It demonstrates a direct link between the spectrum discontinuities and the entropy of two centered black holes in N=4 supersymmetric string theories.

Findings

The dyon spectrum changes discontinuously across walls of marginal stability.

The entropy of two centered small black holes accounts for the spectrum change.

Black holes disappear as the system crosses the walls of marginal stability.

Abstract

The exact spectrum of dyons in a class of N=4 supersymmetric string theories is known to change discontinuously across walls of marginal stability. We show that the change in the degeneracy across the walls of marginal stability can be accounted for precisely by the entropy of two centered small black holes which disappear as we cross the walls of marginal stability.