Black Holes as Fundamental Strings: Comparing the Absorption of Scalars

TL;DR

This paper tests the black hole-string correspondence by comparing scalar absorption rates, finding discrepancies that suggest the relationship may be more complex than previously thought.

Contribution

It provides a detailed comparison of absorption rates, challenging the simplicity of the black hole-string correspondence in near extremal regimes.

Findings

Disagreement between black hole and string absorption rates

Complexity in the black hole-string correspondence

Implications for the correspondence principle

Abstract

The recently proposed ``correspondence principle'' of Horowitz and Polchinski provides a concrete means to relate (among others) black holes with electric NS-NS charges to fundamental strings and correctly match their entropies. We test further this correspondence by examining the greybody factors in the absorption rates of neutral, minimally coupled scalars by a near extremal black hole. Perhaps surprisingly, the results disagree in general with the absorption by weakly coupled strings. Though this does not disprove the correspondence, it indicates that it might not be simple in this region of the black hole parameter space.