  We discuss the cosmological consequences of an interacting model in the dark
sector in which the $\Lambda$ component evolves as a truncated power series of
the Hubble parameter. In order to constrain the free parameters of the model we
carry out a joint statistical analysis involving observational data from
current type Ia supernovae, recent estimates of the cosmic microwave background
shift parameter and baryon acoustic oscillations measurements. Finally, we
adopt a theoretical method to derive the coupled scalar field version for this
non-equilibrium decaying vacuum accelerating cosmology.
