String Junctions and Bound States of Intersecting Branes

TL;DR

This paper investigates the microscopic bound states of intersecting branes, such as string junctions and twisted strings, to explain black hole entropy in string theory.

Contribution

It identifies different descriptions of bound states of intersecting branes, linking massless string junctions and twisted strings to black hole microstates.

Findings

Bound states are described by massless string junctions in some U-frames.

Twisted strings at orbifold singularities also represent these bound states.

These states account for the entropy of four-dimensional black holes.

Abstract

We study four-dimensional black hole configurations which result from wrapping M5-branes on a Calabi-Yau manifold, as well as U-dual realizations. Our aim is to understand the microscopic degrees of freedom responsible for the existence of bound states of multiple branes. The details depend on the chosen U-frame; in some cases, they are massless string junctions. We also identify a perturbative description in which these states correspond to twisted strings of intersecting D3-branes at an orbifold singularity. In each case, these are the preponderant states of the spacetime infrared conformal field theory and account for the entropy of the blackhole.