B decays to radially excited D

Abstract

We discuss the possibility to measure in present experiments, especially LHCb, the non leptonic decay branching ratio $B\to D^{\prime }\pi$, and emphasize phenomenological implications on $B\to D^{\prime }l\nu$ semileptonic decay. We have estimated by lattice QCD the $D^{\prime }$ decay constant $f_{D^{\prime }}$ that parameterizes the $D^{\prime }$ emission contribution to the Class-III non leptonic decay $B^{-}\to D^0{\pi }^{-}$. In addition, we provide a new estimate of the decay constants $f_{D_{s,q}}$ which read $f_{D_s}=252(3)$ MeV and $f_{D_s}/f_D=1.23(1)(1)$.

Comments: 7 pages, 3 figures. Proceedings of the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, Germany