Shape dependence of spontaneous scalarization
  Spontaneous scalarization is an interesting mechanism for modification of
gravity by nonminimal coupling of a scalar field to matter or curvature
invariants in the context of scalar-tensor theories, and its onset is signaled
by linear instability of the scalar field around the corresponding general
relativity solution. We thus perform the linear stability analysis of the
scalar field about general relativity solutions and highlight a crucial
difference between a spherically symmetric profile and a planar symmetric
profile. We clarify that the critical value for the instability is sensitive to
the morphology and that the spontaneous scalarization occurs much more easily
with the planar symmetric shape than with the spherically symmetric shape.
