  We examine the effect of large extra dimensions on vacuum decay in the
Randall-Sundrum (RS) braneworld paradigm. We assume the scalar field is
confined to the brane, and compute the probability for forming an "anti de
Sitter" (AdS) bubble inside a critical flat RS brane. We present the first full
numerical solutions for the brane instanton considering two test potentials for
the scalar field. We explore the geometrical impact of thin and thick bubble
walls, and compute the instanton action in a range of cases. We conclude by
commenting on a more physically realistic potential relevant for the standard
model Higgs. For bubbles with large backreaction, the extra dimension has a
dramatic effect on the tunnelling rate, however, for the weakly backreacting
bubbles more relevant for realistic Standard Model potentials, the extra
dimension has little impact.
