The correspondence between rotating black holes and fundamental strings

TL;DR

This paper explores the complex relationship between rotating black holes and fundamental strings, proposing a refined correspondence framework that includes dynamic and non-stationary configurations to resolve existing puzzles.

Contribution

It introduces a new scheme for the string-black hole correspondence that accounts for rotation and dynamical features, extending previous models to include all phases except near-extremal Kerr black holes.

Findings

A correspondence scheme that includes rotating black holes and strings.

Identification of puzzles related to high-spin states and their matching.

Proposition of dynamical and non-stationary configurations to resolve these puzzles.

Abstract

The correspondence principle between strings and black holes is a general framework for matching black holes and massive states of fundamental strings at a point where their physical properties (such as mass, entropy and temperature) smoothly agree with each other. This correspondence becomes puzzling when attempting to include rotation: At large enough spins, there exist degenerate string states that seemingly cannot be matched to any black hole. Conversely, there exist black holes with arbitrarily large spins that cannot correspond to any single-string state. We discuss in detail the properties of both types of objects and find that a correspondence that resolves the puzzles is possible by adding dynamical features and non-stationary configurations to the picture. Our scheme incorporates all black hole and string phases as part of the correspondence, save for one outlier which remains enigmatic: the near-extremal Kerr black hole. Along the way, we elaborate on general aspects of the correspondence that have not been emphasized before.