Scalar mode analysis of the warped Salam-Sezgin model

TL;DR

This paper analyzes scalar perturbations in the warped Salam-Sezgin model, revealing the significance of non-constant modes in the effective theory and confirming the stability of warped solutions.

Contribution

It provides a detailed reduction of scalar fluctuations to constant and non-constant modes, highlighting the importance of non-constant modes often overlooked in previous studies.

Findings

Non-constant scalar modes are crucial for the 4D effective theory.

Warped solutions are stable and free of instabilities.

Explicit solutions for scalar modes are derived.

Abstract

We study the scalar perturbation sector of the general axisymmetric warped Salam-Sezgin model with codimension-2 branes. We focus on the perturbations which mix with the dilaton. We show that the scalar fluctuations analysis can be reduced to studying two scalar modes of constant wavefunction, plus modes of non-constant wavefunction which obey a single Schroedinger equation. From the obtained explicit solution of the scalar modes, we point out the importance of the non-constant modes in describing the four dimensional effective theory. This observation remains true for the unwarped case and was neglected in the relevant literature. Furthermore, we show that the warped solutions are free of instabilities.