Extended Metastable Dark Energy
  The metastable dark energy scenario is revisited by assuming that the current
false vacuum energy density is the remnant from a primeval inflationary stage.
The zero temperature scalar field potential is here described by an even power
series up to order six which depends on 3 free parameters: the mass of the
scalar field ($m$), the dimensionless ($\lambda$) specifying the standard
self-interaction term, and a free cutoff mass scale ($M$) quantifying all
possible deviations from the degenerate false vacuum state. The current
$\Lambda$CDM model is a consequence of the very long decay time of the false
vacuum which although finite is much greater than the current age of the
Universe. This result remains valid for arbitrary combinations of the $m/M$
ratio which can analytically be determined in the thin-wall approximation and
numerically calculated outside this limit. Unlike many claims in the literature
the vacuum dominance may be temporary. The finiteness of the decay time
suggests that the ultimate stage of the observed Universe in such a scenario
will not be driven by a de Sitter type cosmology.
