Brane world creation from flat or almost flat space in dynamical tension string theories

TL;DR

This paper explores a novel brane world scenario emerging from dynamical tension string theories, where matter and gravity are confined between two surfaces with infinite tension, resulting in a natural brane formation from flat or nearly flat spaces.

Contribution

It introduces a new stringy brane world model based on dynamical tension theories with two types of strings and conformally related flat metrics, demonstrating brane creation from almost flat spaces.

Findings

Brane worlds can arise naturally from flat space configurations.

Infinite tension strings are confined between two surfaces, creating effective branes.

The model resolves backreaction issues using a universe creation mechanism from nearly flat spaces.

Abstract

There is great interest in the construction of brane worlds, where matter and gravity are forced to be effective only in a lower dimensional surface , the brane . How these could appear as a consequence of string theory is a crucial question and this has been widely discussed. Here we will examine a distinct scenario that appears in dynamical tension theories and where string tension is positive between two surfaces separated by a short distance and at the two surfaces themselves the string tensions become infinite, therefore producing an effective confinement of the strings and therefore of all matter and gravity to the space between these to surfaces, which is in fact a new type of stringy brane world scenario. The basic formulation for obtaining this scenario consist of assuming two types of strings characterized by a different constant of integration related to the spontaneous string tension generation. These string tension multiplied by the embedding metric define conformally related metrics that both satisfy Einsteins equation. The braneworlds appear very naturally when these two metrics are both flat spaces related by a special conformal transformation. The two types of string tensions are determined and they blow up at two close expanding surfaces. A puzzling aspect appears then: the construction is based on flat spaces, but then there are also strings with very large tension near the boundaries of the braneworld,so can the back reaction from the infinite tension strings destroy the flat space background?. Fortunatelly that can be resolved using the mechanism Universe creation from almost flat (or empty) spaces, which incorporates a gas of very large string tensions in a membrane, studied before in 1+1 membranes in a 2+1 embedding space and now is generalized for a 1+(D-2) membrane moving in a 1+(D-1) space.