Coupled Dark Energy field variation
  The variation of the dark energy field is found under the assumption that the dark energy is parametric and interacts with the cold dark matter. Considering that the variation of the field could not exceed the Planck mass, we obtain bounds on the coupling and adiabatic coefficients. Three parameterizations of the adiabatic coefficients are considered and two coupling terms where the energy flows from dark energy to dark matter, or the other way around. 
Roberto Carlos Garc\'ia-Z\'u\~niga and Germ\'an Izquierdo
astro-ph.CO