Effect of non-conformal deformation on the gapped quasi-normal modes and the holographic implications

TL;DR

This paper investigates how non-conformal deformations affect the spectral properties of quasinormal modes in holographic black branes, revealing increased convergence domains and specific dispersion relations.

Contribution

It introduces a holographic analysis of non-conformal effects on quasinormal modes, pole-skipping, and the derivative expansion's convergence in a dilaton gravity setup.

Findings

Non-conformality induces gapped dispersion relations in quasinormal modes.

Presence of non-conformality increases the radius of convergence of the derivative expansion.

Pole-skipping points are classified based on dispersion relations, revealing non-conformal effects.

Abstract

The spectral curve of quasinormal modes for a massive real scalar field in the background of a non-conformal black brane geometry has been obtained by utilizing a Frobenius type near-horizon expansion. The gauge/gravity duality maps this to the computation of spectral curve of a massive scalar operator $\mathcal{O}_{\phi}$ for a large-$N$ conformal field theory with irrelevant type non-conformal deformation. In this context, non-conformality has been holographically introduced by using the Einstein-dilaton theory with Liouville type dilaton potential as the bulk theory. It has been observed that the obtained quasinormal modes are characterized by specific gapped dispersion relations. The pole-skipping points have also been computed and classified based upon different dispersion relations satisfied by them. The effect of non-conformality is evident from these results. The radius of convergence of the derivative expansion in the momentum space is then computed from the critical points of the spectral curve. It has been observed that presence of non-conformality increases the domain of applicability of the derivative expansion in momentum space, as it increases the radius of convergence for a given conformal dimension. The comparison between the convergence radii and the absolute momenta corresponding to lowest order pole-skipping points also leads to some interesting findings.