National audienceSemileptonic B decays are of primary importance since, for example, they participate very strongly in the accurate determination of the CKM matrix element Vcb which represents a test of the Standard Model. However, there are many puzzling features associated with the semileptonic b → c data, which have appeared during the last ten years such as the so-called "1/2 versus 3/2 puzzle" which corresponds to the difference between theoretical predictions and experimental measurements of semileptonic branching ratios of Bbar→ D ** lnu. In many theoretical approaches (HQET, heavy quark expansion, quark model, Lattice QCD with quenched calculation, etc...), branching ratios corresponding to the decay Bbar→ D ** lnu were calculated using the infinite mass limit. That is the reason why, in order to address the aforementioned questions, we propose to determine for the first time the physical parameters and then the branching ratios using "real" charmed quarks having a finite mass
