Tubular Branes in Fluxbranes

TL;DR

The paper develops exact supergravity solutions for self-gravitating tubular p-branes in fluxbrane backgrounds, systematically constructing spherical and tubular branes via dimensional reduction of Euclidean rotating black holes and their string/M-theory embeddings. It shows how fluxbranes can remove conical singularities and produce regular cores in several setups, including string loops and M5-brane intersections, while also exploring bound states with dissolved F-strings and D0-branes. However, many configurations retain conical defects or fail to achieve stable equilibrium without external fields, raising questions about the stability and physical relevance of self-gravitating tubular branes and their connection to dielectric/DBI descriptions. The work highlights both opportunities (regular horizons, AdS_3 x S^2 throats in special limits) and limitations (whether self-gravity can yield stable tubes) and outlines directions for further stability analyses and off-shell explorations.

Abstract

We describe the construction of new configurations of self-gravitating p-branes with worldvolume geometries of the form R^{1,p-s} x S^s, with 1\leq s\leq p, ie, tubular branes. Since such branes are typically unstable against collapse of the sphere, they must be held in equilibrium by a fluxbrane. We present solutions for string loops with non-singular horizons, as well as M5-branes intersecting over such loops. We also construct tubular branes which carry in their worldvolume a dissolved, lower dimensional brane (as in the dielectric effect), or an F-string. However, the connection between our solutions and related configurations that have been studied earlier in the absence of brane self-gravity, is unclear. It is argued that, at least in some instances, the self-gravitating solutions do not appear to be able to reproduce stable configurations of tubular branes.