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arXiv · 2605.02820

Gravitational-Bumblebee perturbations: Exact decoupling and isospectrality

Abstract

In this paper, we present the exact decoupling of the full metric and bumblebee field perturbations in a Schwarzschild-like background. The coupled system reduces to four decoupled master equations, revealing in each parity sector a Schwarzschild-like gravitational sector and a Lorentz-violating Maxwell-like vector sector. While Lorentz violation modifies the propagation speed of the emergent vector modes, we demonstrate that the gravitational master modes exhibit a ``dynamical immunity'' to the non-minimal Lorentz-violating coupling, and that the odd- and even-parity perturbations remain strictly isospectral. Our work provides a rare example in which Lorentz-violating couplings reshape the field reconstruction while leaving the gravitational ringdown spectrum intact. This mismatch in propagation speeds suggests a possible timing signature of bumblebee vector dynamics in black hole perturbations, offering a theoretical route to testing spontaneous Lorentz symmetry breaking in the era of multi-messenger astronomy.

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BibTeXRIS

Hui-Fa Liu, Wentao Liu, Yu-Xiao Liu, Qi Su, Ding-fang Zeng. 2026-05-04. Gravitational-Bumblebee perturbations: Exact decoupling and isospectrality. https://arxiv.org/abs/2605.02820

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