On the significance of B-decays to the radially excited D

We discuss the possibilities of testing the recent claims of a relatively large B→D′B→D′ transition form factor through the non-leptonic B¯0→D′+π− and B−→D′0π− decay modes. To estimate the width of the latter we need the decay constant of the radially excited D  -meson that we computed in lattice QCD with Nf=2Nf=2 dynamical flavors and after taking the continuum limit we found fD′=117(25) MeVfD′=117(25) MeV. We also provide an update for the values of the D-meson decay constants obtained by using maximally twisted mass QCD.