Tachyonic (In)stability in Randall-Sundrum Braneworld Scenarios
Abstract
Low-energy effective theories provide a natural description of four-dimensional physics in higher-dimensional geometries, where the imprint of the bulk geometry appears as parameters of the lower-dimensional theory. Inspired by the Damour-Esposito-Farése (DEF) model of spontaneous scalarization in first generation Scalar-Tensor theories of gravity, we investigate the possibility of tachyonic instability and spontaneous scalarization in braneworld scenarios. We consider the two-brane Randall-Sundrum model where the low-energy effective theory on either brane is of scalar-tensor nature with the extra-dimensional radion playing the role of the scalar. We have determined the possibilities for tachyonic (in)stability of the radion field on either brane in three scenarios: the Randall-Sundrum (RS) model with fine-tuning conditions in which the potential of the radion field vanishes identically, the RS model without fine-tunings where the radion potential arises purely from the gravity sector and the RS model with a bulk stabilizing field that generates a radion potential with a minimum. With the bulk stabilizing field, we have found that on-brane matter with T>0 changes the VEV of the radion, destroying the resolution of the gauge hierarchy problem, whereas on-brane matter with T<0 does not alter the stability and VEV of the radion. We further determined the exact condition of tachyonic (in)stability of radion field with the on-brane dS4 and AdS4 geometries.
Versions
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BibTeX
@misc{karmakar2026tachyonic,
title = {{Tachyonic (In)stability in Randall-Sundrum Braneworld Scenarios}},
author = {Abhirup Karmakar and Soumitra SenGupta},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.18403},
eprint = {2605.18403},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.18403},
}
RIS
TY - UNPB
TI - Tachyonic (In)stability in Randall-Sundrum Braneworld Scenarios
AU - Abhirup Karmakar
AU - Soumitra SenGupta
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2605.18403
UR - https://arxiv.org/abs/2605.18403
AB - Low-energy effective theories provide a natural description of four-dimensional physics in higher-dimensional geometries, where the imprint of the bulk geometry appears as parameters of the lower-dimensional theory. Inspired by the Damour-Esposito-Farése (DEF) model of spontaneous scalarization in first generation Scalar-Tensor theories of gravity, we investigate the possibility of tachyonic instability and spontaneous scalarization in braneworld scenarios. We consider the two-brane Randall-Sundrum model where the low-energy effective theory on either brane is of scalar-tensor nature with the extra-dimensional radion playing the role of the scalar. We have determined the possibilities for tachyonic (in)stability of the radion field on either brane in three scenarios: the Randall-Sundrum (RS) model with fine-tuning conditions in which the potential of the radion field vanishes identically, the RS model without fine-tunings where the radion potential arises purely from the gravity sector and the RS model with a bulk stabilizing field that generates a radion potential with a minimum. With the bulk stabilizing field, we have found that on-brane matter with T>0 changes the VEV of the radion, destroying the resolution of the gauge hierarchy problem, whereas on-brane matter with T<0 does not alter the stability and VEV of the radion. We further determined the exact condition of tachyonic (in)stability of radion field with the on-brane dS_4 and AdS_4 geometries.
ER -