Mr Florian Bernlochner (University of Victoria (CA))
Some long-standing problems in the experimental data for semileptonic b -> c l nu decay rates have resisted attempts to resolve them, despite substantial efforts. We show that the presence of a relatively large decay rate into radially-excited D-mesons may alleviate several of these tensions simultaneously. In particular, their presence could help explaining the discrepancy between model calculations and experimental results for the first orbitally-excited doublets, known as the “1/2 vs. 3/2 puzzle”. In order to substantiate our hypothesis, we estimate the decay rate into the first two radially excited charmed states using a quark-model and light-cone sum-rules, finding that it is not unreasonable to expect O(1%) branching fraction for these decays.