A comment on $p$-branes of ($p+3$)$\rm{d}$ string theory

TL;DR

This paper discusses the necessity of negative tension NS-NS p-branes in string theory for certain background geometries and suggests they may be the true background branes in our universe, contrasting with D-branes.

Contribution

It proposes that negative tension NS-NS p-branes are essential for specific background geometries and may be the fundamental branes in our universe, challenging the D-brane dominance.

Findings

Negative tension NS-NS p-branes are crucial for $R_2$ and $R_2/Z_n$ geometries.

Standard codimension-2 brane solutions implicitly include negative tension NS-branes.

Conjecture that NS-NS branes could be the true background branes in our spacetime.

Abstract

We argue that in ($p+3$)d string theory the existence of NS-NS type $p$-brane with negative tension is essential to obtain background geometry $R_2$ or $R_2 / Z_n$ on the transverse dimensions, and the usual codimension-2 brane solutions with these background geometries already contain the negative tension NS-brane implicity in their ansatz. Such an argument leads us, in the context of brane world scenarios, to a conjecture that true background $p$-brane immanent in our spacetime may perhaps be NS-NS type brane, rather than D-brane.