Four-Dimensional Greybody Factors and the Effective String

Abstract

Recently Maldacena and Strominger found that the calculation of greybody factors for $D=5\mathrm{}$ 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 $D=4\mathrm{}$ 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 $T^7$.