Absorption of angular momentum by black holes and D-branes

TL;DR

This paper investigates how higher angular momentum scalar waves are absorbed by black holes and D-branes, revealing the importance of string splitting and tension tuning for matching cross sections.

Contribution

It introduces a D-brane model with a tension set to the geometric mean of D-string and effective string tensions, explaining absorption cross sections for higher angular momentum modes.

Findings

Correct volume dependence achieved with tension tuning.

String splitting into multiple strings reproduces angular momentum effects.

Energy dependence of cross sections derived from vibrational partitioning.

Abstract

We consider the absorption of higher angular momentum modes of scalars into black holes, at low energies, and ask if the resulting cross sections are reproduced by a D-brane model. To get the correct dependence on the volume of the compactified dimensions, we must let the absorbing element in the brane model have a tension that is the geometric mean of the tensions of the D-string and an effective stringlike tension obtained from the D-5-brane; this choice is also motivated by T-duality. In a dual model we note that the correct dependence on the volume of the compact dimensions and the coupling arise if the absorbing string is allowed to split into many strings in the process of absorbing a higher angular momentum wave. We obtain the required energy dependence of the cross section by carrying out the integrals resulting from partitioning the energy of the incoming quantum into vibrations of the string.