Radion in Multibrane World

TL;DR

This paper analyzes radion dynamics in multibrane models, deriving effective Lagrangians, examining mode couplings, and exploring implications for gravity and radion emission in both compact and non-compact scenarios.

Contribution

It provides a detailed calculation of radion effective Lagrangian and mode couplings in multibrane setups, including the decompactification limit and non-compact cases.

Findings

Radion effective Lagrangian derived for three-brane systems.

Normalizable dilaton mode exists even in non-compact models.

Gravity behavior varies with brane tension configurations.

Abstract

The radion dynamics related to the presence of moving branes with both positive or negative tensions is studied in the linearized approximation. The radion effective Lagrangian is computed for a compact system with three branes and in particular we examine the decompactification limit when one brane is sent to infinity. In the non-compact case we calculate the coupling of the gravitational modes (graviton, dilaton and radion) to matter on the branes. The character of gravity on the two branes for all possible combinations of brane tensions is also discussed. It turns out that one can have a normalizable dilaton mode even in the non-compact case. Finally, we speculate on the role of moving branes as a possible source of radion emission.