Speaker
Description
There is a significant gap between the inclusive measurement of the $B \rightarrow X_{c} l \nu$ branching fraction and the sum of the measurements of the exclusive $B \rightarrow X_{c} l \nu$ channels. The dominant contributions $B \rightarrow D^{*} l \nu$ and $B \rightarrow D l \nu$ are precisely known but the branching fractions of $B \rightarrow D^{**} l \nu$ have higher uncertainties. Here, the $D^{**}$ is an orbitally excited charmed meson, which can decay into $D^{*} \pi$ and $D \pi$. The decay $B \rightarrow D^{(*)} \pi\pi l \nu$ with two bachelor pions in the final state has so far only been observed by the Babar collaboration.
Over the course of about 10 years the Belle collaboration has recorded about 772 million $B\overline{B}$ pairs produced in $e^{+} e^{-} \rightarrow \Upsilon(4S)$ at the KEKB asymmetric-energy $e^{+} e^{-}$ collider. The status of the measurement of the branching fraction of $B \rightarrow D^{(*)} \pi l \nu$ as well as $B \rightarrow D^{(*)} \pi\pi l \nu$ using the full Belle data sample will be presented. In addition, an analysis of the invariant $D^{(*)} \pi$ mass distribution will be shown.
| Are you are a member of the APS Division of Particles and Fields? | Yes |
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