In this work we investigate the interaction between dark matter and dark energy for a coupling that obeys the Wang-Meng decaying law , \rho _ { { DM } } \propto ( 1 + z ) ^ { 3 - \epsilon } , and the Barboza-Alcaniz dark energy parametric model , w = w _ { 0 } + w ^ { \prime } _ { 0 } z ( 1 + z ) / ( 1 + z ^ { 2 } ) .
Theoretically , we show that the coupling constant , \epsilon , should satisfy the physical constraint \epsilon \geq 0 .
We use the most recent data of type Ia supernovae , baryon acoustic oscillations , cosmic microwave background and the Hubble expansion rate function to constrain the free parameters of the model .
From a purely observational point of view , we show that is not possible to discard values of the coupling constant in the unphysical region \epsilon < 0 .
We show that the uncoupled case , \epsilon = 0 , is in better agreement with the data than any of coupled models in the physical region .
We also find that all physically acceptable interaction in dark sector lies in the narrow range 0 < \epsilon \leq 0.034 ( 95 \% CL ) .