Real part emergence in purely imaginary quasinormal modes in perturbed de Sitter braneworlds
- 1Lanzhou University
Abstract
A bstract : For braneworlds with infinite extra dimensions, an analysis of the stability of the characteristic spectrum is essential for understanding their dynamical properties. In this study, we investigate the stability of the gravitational quasinormal-mode (QNM) spectrum of a thick de Sitter braneworld with a noncompact extra dimension. The unperturbed background supports a localized graviton zero mode and a tower of purely imaginary QNMs. We first reconstruct the response of the warp factor and tensor effective potential to a smooth double-kink deformation of the bulk scalar field, and then introduce a superpotential deformation that parametrizes the resulting double-barrier structure. The deformed frequency-domain spectrum develops QNM pairs with nonzero real parts. For the representative family studied here, a weak deformation can already generate a complex branch, although the least-damped pole remains purely imaginary in part of the parameter range. In the time domain, the QNM-dominated channel exhibits a transient damped oscillatory stage, whereas the original-potential evolution becomes dominated by the zero-mode sector at late times over the simulated interval. These results identify the double-barrier geometry as the model-specific realization of a more general sensitivity of outgoing, non-self-adjoint spectra. They establish a robust model-level mechanism for oscillatory QNM imprints and provide a dimensionless benchmark for future source-to-detector analyses; quantitative detector detectability and cosmological-parameter inference require source, response, and noise modeling beyond the present analysis.
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BibTeX
@article{jia2026real,
title = {{Real part emergence in purely imaginary quasinormal modes in perturbed de Sitter braneworlds}},
author = {Hai-Long Jia and Wen-Di Guo and Yun-Tao Gu and Yu-Xiao Liu},
journal = {Journal of High Energy Physics},
year = {2026},
month = oct,
doi = {10.1007/jhep10(2026)265},
url = {https://link.springer.com/article/10.1007/JHEP10(2026)265},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Real part emergence in purely imaginary quasinormal modes in perturbed de Sitter braneworlds
AU - Hai-Long Jia
AU - Wen-Di Guo
AU - Yun-Tao Gu
AU - Yu-Xiao Liu
PY - 2026
DA - 2026/10/28
JO - Journal of High Energy Physics
DO - 10.1007/jhep10(2026)265
UR - https://link.springer.com/article/10.1007/JHEP10(2026)265
AB - A bstract : For braneworlds with infinite extra dimensions, an analysis of the stability of the characteristic spectrum is essential for understanding their dynamical properties. In this study, we investigate the stability of the gravitational quasinormal-mode (QNM) spectrum of a thick de Sitter braneworld with a noncompact extra dimension. The unperturbed background supports a localized graviton zero mode and a tower of purely imaginary QNMs. We first reconstruct the response of the warp factor and tensor effective potential to a smooth double-kink deformation of the bulk scalar field, and then introduce a superpotential deformation that parametrizes the resulting double-barrier structure. The deformed frequency-domain spectrum develops QNM pairs with nonzero real parts. For the representative family studied here, a weak deformation can already generate a complex branch, although the least-damped pole remains purely imaginary in part of the parameter range. In the time domain, the QNM-dominated channel exhibits a transient damped oscillatory stage, whereas the original-potential evolution becomes dominated by the zero-mode sector at late times over the simulated interval. These results identify the double-barrier geometry as the model-specific realization of a more general sensitivity of outgoing, non-self-adjoint spectra. They establish a robust model-level mechanism for oscillatory QNM imprints and provide a dimensionless benchmark for future source-to-detector analyses; quantitative detector detectability and cosmological-parameter inference require source, response, and noise modeling beyond the present analysis.
SN - 1029-8479
ER -