DBI analog of a decaying vacuum cosmology
  In this work I discuss the dynamical and thermodynamical equivalence between
a general k-essence scalar field cosmology and an arbitrary cosmological model
with a decaying vacuum, thus generalizing the approach proposed by Maia and
Lima [Phys. Rev. D {\bf 65}, 083513 (2002)]. The formalism obtained is quite
general and holds for any non-canonical scalar field model. As a special case I
derive a Dirac-Born-Infeld (DBI) model with an exponential potential and
constant speed of sound, and show that it is equivalent to a cosmological model
with decay law $\Lambda(H) = 3\beta H^2$.
