Quantum Corrections to Black Hole Entropy in String Theory

TL;DR

This paper calculates quantum corrections to black hole entropy within string theory, revealing a divergence linked to string state growth, and suggests the classical entropy formula should be interpreted through string states near the horizon.

Contribution

It provides a one-loop string theory computation of black hole entropy corrections, highlighting the role of string states and divergences near the horizon.

Findings

The one-loop correction is modular invariant and UV finite.

An infrared divergence indicates a near-horizon instability.

The divergence relates to the Hagedorn transition in string theory.

Abstract

The one-loop contribution to the entropy of a black hole from field modes near the horizon is computed in string theory. It is modular invariant and ultraviolet finite. There is an infrared divergence that signifies an instability near the event horizon of the black hole. It is due to the exponential growth of the density of states and the associated Hagedorn transition characteristic of string theory. It is argued that this divergence is indicative of a tree level contribution, and the Bekenstein-Hawking-Gibbons formula for the entropy should be understood in terms of string states stuck near the horizon.