Wormhole creation by quantum tunnelling
  We study the process of quantum tunnelling in self-interacting scalar field theories with non-minimal coupling to gravity. In these theories gravitational instantons can develop a neck -- a feature prohibited in theories with minimal coupling, and describing the nucleation of geometries containing a wormhole. We also clarify the relationship of neck geometries to violations of the null energy condition. 
Lorenzo Battarra, George Lavrelashvili and Jean-Luc Lehners
gr-qc hep-th