Four-dimensional greybody factors and the effective string

TL;DR

This paper extends the analysis of greybody factors to four-dimensional black holes with four U(1) charges, providing evidence for their description as effective strings, similar to previous five-dimensional cases, by relating them to M-theory brane intersections.

Contribution

It demonstrates that four-dimensional black holes with four U(1) charges can also be described by effective strings, generalizing earlier five-dimensional results and linking to M-theory brane intersections.

Findings

Greybody factors for 4D black holes match effective string predictions

Effective string description applies to 4D black holes with four charges

Connection established between black hole microstates and M-theory brane intersections

Abstract

Recently Maldacena and Strominger found that the calculation of greybody factors for $D=5$ black holes carrying three U(1) charges gives striking new evidence for their description as multiply wound effective strings. Here we show that a similar result holds for $D=4$ black holes with four $U(1)$ charges. In this case the effective string may be thought of as the triple intersection of the 5-branes in M-theory compactified on $T^7$.