Scattering length of the \DPi (left) and \DstarPi (right) interaction, for the two isospin channels that characterize the systems. They are extracted from a simultaneous $\chi^2$ minimization to the experimental correlation functions. The red (orange) areas represent the resulting confidence intervals for a 68\% (95\%) probability. The dashed lines correspond to Coulomb interaction only, as the scattering lengths of the strong interaction vanish. As comparison, the available theoretical predictions~, listed in Tables~\ref{tab:scatParamPi} and~\ref{tab:scatParamK} are shown as well.