Remarks on the Classical Size of D-Branes

TL;DR

This paper examines the classical size of extremal D-branes in supergravity, revealing how duality and dimensional scales influence their perceived size and core structure.

Contribution

It introduces criteria for defining the classical size of D-branes and explores how duality relates the core size to fundamental string and Planck scales.

Findings

The size of the strong-coupling region for p<3 branes equals the asymptotic string scale.

The eleven-dimensional Planck scale appears in the classical 0-brane solution.

The ten-dimensional Planck scale is relevant for the D-instanton solution.

Abstract

We discuss different criteria for `classical size' of extremal Dirichlet p-branes in type-II supergravity. Using strong-weak coupling duality, we find that the size of the strong-coupling region at the core of the (p<3)-branes, is always given by the asymptotic string scale, if measured in the weakly coupled dual string metric. We also point out how the eleven-dimensional Planck scale arises in the classical 0-brane solution, as well as the ten-dimensional Planck scale in the D-instanton solution.