Speaker
Dr
Benoit Blossier
(CNRS/Laboratoire de Physique Théorique d'Orsay)
Description
Understanding the composition of final states in B --> Xc l nu could help
to get a feedback on the persisting disagreement between exclusive and
inclusive determinations of Vcb. In particular the series of orbital
excitations D** and radial excitations (D', D*') has received a lot of
attention; a misinterpretation as a scalar state of the (D' --> D pi)
spectrum tail could have induced an experimental overestimate of the broad
states contribution to the total B --> Xc l nu width with respect to
theoretical expectations, all of them made however in the infinite mass
limit: it is the so-called 1/2 vs 3/2 puzzle. We will describe first
attempts to measure on the lattice form factors of B --> D** l nu
at realistic quark masses. Cleaner processes, like hadronic decays B -->
D** pi and semileptonic decays Bs --> Ds** l nu in the strange sector
have recently been examined by phenomenologists, putting new interesting
ideas on those issues with, again, the need of lattice inputs.
