Asymmetric D-braneworld

TL;DR

This paper investigates the Randall-Sundrum D-braneworld model without Z_2 symmetry, revealing that gauge fields do not couple to gravity at leading order, suggesting non-BPS states might be necessary for standard gravity recovery.

Contribution

It analyzes the asymmetric D-braneworld model using long wave approximation, showing the persistent issue of gauge-gravity coupling failure without Z_2 symmetry.

Findings

Gauge fields do not couple to gravity at leading order in the asymmetric model.

Removing Z_2 symmetry does not restore usual gravitational coupling.

Non-BPS states may be required to recover standard gravity.

Abstract

In recent papers on Randall-Sundrum D-braneworld model with Z_2 symmetry, it was shown that the effective gravity does not work as usual, that is, the gravity does not couple to the gauge field localised on the brane in a usual way. At first glance there are two possibilities to avoid this serious problem. One is to remove the Z_2 symmetry and another is to consider a non-BPS state. In this paper we analyze the Randall-Sundrum D-braneworld model without Z_2 symmetry by long wave approximation. The result is unexpected one, that is, the gauge field does not couple to the gravity on the brane in the leading order again. Therefore the remaining possibility to recover the conventional gravitational theory would be non-BPS cases.