A fresh look at the determination of |V_cb| from B-> D^* l nu


Abstract in English

We use recent Belle results on $bar{B}^0rightarrow D^{*+}l^-bar{ u}_l$ decays to extract the CKM element $|V_{cb}|$ with two different but well-founded parameterizations of the form factors. We show that the CLN and BGL parameterizations lead to quite different results for $|V_{cb}|$ and provide a simple explanation of this unexpected behaviour. A long lasting discrepancy between the inclusive and exclusive determinations of $|V_{cb}|$ may have to be thoroughly reconsidered.

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