Vertexing and Tracking Software at Belle II

Abstract: Belle II is a $B$ factory experiment aiming to start physics data taking in 2017. It is currently being set up at the SuperKEKB accelerator at the KEK facility in Tsukuba (Japan), an asymmetric $e^+e^-$ collider which aims to achieve an unprecedented instantaneous luminosity of $8\cdot10^{35} \textrm{Hz}/\textrm{cm}^2$. This forty-fold increase over predecessor experiments is achieved by employing a novel nano-beam scheme. Originally developed for the now-defunct SuperB experiment, this scheme allows a significant increase in luminosity at only modest increases of beam currents. Challenges for the vertex detector result from increased data and background rates. At full luminosity, physics data will be recorded at a rate of $30\,\textrm{kHz}$. The radiation-hard DEPFET-sensors of the innermost layer of the vertex detector will be read out employing a novel data-reduction scheme using selective detector read out based on online reconstruction of event data. Belle II uses a software framework in which data handling is unified between various data processing modules. In this way, tasks can be divided flexibly and the same software framework can be used for a diversity of tasks ranging from the high-level trigger to final processing of plots for publications. Tracking and vertexing modules are currently under development and we will discuss their features.