Scattering length of the $\mathrm{D}\pi$ (left) and $\mathrm{D^*}\pi$ (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 IV and V are shown as well.