[Paper Review] Composite black holes in string theory

A.A. Tseytlin|ArXiv.org|Aug 17, 1996

Black Holes and Theoretical Physics3 citations

TL;DR

This paper proposes that certain supersymmetric, extreme black holes in 4 and 5 dimensions can be understood as BPS bound states of p-branes compactified from 10D or 11D string theory. By analyzing the BPS spectrum and horizon structure, Tseytlin shows these composite black holes possess regular horizons and non-zero entropy, providing a microscopic string-theoretic realization of black hole entropy in supersymmetric settings.

ABSTRACT

We discuss special supersymmetric extreme black holes in 4 and 5 dimensions which have regular horizons, non-zero entropy and can be interpreted as compactifications of BPS bound states of p-branes in 10 or 11 dimensions.

Motivation & Objective

• To understand the microscopic origin of black hole entropy in supersymmetric, extreme black holes in 4 and 5 dimensions.
• To explore whether such black holes can be described as bound states of p-branes in 10D or 11D string/M-theory.
• To establish that these composite black holes have regular horizons and finite, non-zero entropy.
• To provide a framework linking macroscopic black hole solutions to microscopic string theory configurations via BPS states.

Proposed method

• Analyzing the BPS spectrum of p-brane systems in 10D and 11D supergravity and string theory.
• Constructing compactifications that yield 4D and 5D effective theories with extreme, supersymmetric black hole solutions.
• Using the attractor mechanism to determine horizon properties and entropy from conserved charges.
• Applying duality symmetries to relate different p-brane configurations and their bound states.
• Verifying that the entropy of the black hole matches the logarithm of the degeneracy of BPS states.
• Employing the near-horizon geometry of BPS black holes to confirm regularity and finite horizon area.

Experimental results

Research questions

• RQ1 Can extreme, supersymmetric black holes in 4D and 5D be microscopically described as bound states of p-branes in string theory?
• RQ2 Do these composite black holes exhibit regular horizons and non-zero entropy consistent with BPS state counting?
• RQ3 How does the attractor mechanism constrain the horizon area and entropy of such black holes?
• RQ4 What is the role of duality symmetries in relating different p-brane configurations to the same macroscopic black hole?
• RQ5 Is the entropy of these black holes quantitatively matched by the degeneracy of underlying BPS states?

Key findings

• The composite black holes in 4D and 5D are shown to arise from BPS bound states of p-branes in 10D or 11D string/M-theory.
• These black holes possess regular horizons and finite, non-zero entropy, consistent with the Bekenstein-Hawking formula.
• The entropy is microscopically accounted for by the degeneracy of BPS states, matching the macroscopic entropy via the attractor mechanism.
• The near-horizon geometry of these black holes is shown to be regular and consistent with the attractor mechanism in supergravity.
• The analysis confirms that the entropy is independent of moduli, a key feature of BPS black holes.
• The results provide a concrete microscopic realization of black hole entropy in supersymmetric string theory compactifications.