Exact Tunneling Solutions in Minkowski Spacetime and a Candidate for   Dark Energy
  We study exact tunneling solutions in scalar field theory for potential barriers composed of linear or quadratic patches. We analytically continue our solutions to imaginary Euclidean radius in order to study the profile of the scalar field inside the growing bubble. We find that generally there is a non-trivial profile of the scalar field, generating a stress-energy tensor, that depending on the form of the potential, can be a candidate for dark energy. 
Georgios Pastras
hep-th gr-qc hep-ph