2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/50698We show the instability of two self-tuning brane world models with gauge invariant linear perturbation theory. This general method confirms a known instability of the original model with vanishing bulk potential. We also show the dynamical instability of a recently proposed self-tuning "smooth" brane model and its limit, the Randall-Sundrum model. Astonishingly, we also find instability under purely gravitational perturbations.11 pages, no figuresHigh Energy Physics - Theorytext