Christian Pulvermacher (KIT)
Belle II is an experiment being built at the $e^+e^-$ SuperKEKB B factory, and will record decays of a large number of $B \bar B$ pairs. This pairwise production of $B$ mesons allows analysts to use one correctly reconstructed $B$ meson to deduce the four-momentum and flavour of the other (signal-side) $B$ meson, without reconstructing any of its daughter particles. It also permits, in conjunction with a signal-side selection, to account for all tracks and calorimeter signals in an event and thus get a cleaner sample, e.g. for decays containing neutrinos. I will present a software framework for Belle II that reconstructs $B$ mesons in many decay modes with minimal user intervention. It does so by reconstructing particles in user-supplied decay channels, and then in turn using these reconstructed particles in higher-level decays. This hierarchical reconstruction allows to cover a relatively high fraction of all $B$ decays by specifying a limited number of particle decays. Multivariate classification methods are used to achieve a high signal-to-background ratio in each individual channel. The entire reconstruction, including the application of precuts and classifier trainings, is automated to a high degree and will allow users to easily add new channels or to retrain on analysis-specific Monte Carlo samples.
Christian Pulvermacher (KIT) Thomas Keck (KIT)
Martin Heck (KIT, Karlsruhe) Michael Feindt (KIT) Thomas Kuhr (KIT)