Speaker
Description
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. Main operation of SuperKEKB has started in March 2019, with the full detector installed; this first running period ended in July. The machine reached a peak luminosity of $1.2\times 10^{34}$ cm$^{-2}$s$^{-1}$, and Belle II recorded a data sample of about 6.5 fb$^{-1}$. Data taking will resume in October 2019. Already this early data set, with specifically designed triggers, offers the possibility to search for a large variety of dark sector particles in the GeV mass range, complementary to LHC and to dedicated low energy experiments; these searches will benefit from more data which will be accumulated in the upcoming Fall/Winter run. This talk will review the state of the dark sector searches at Belle II with a focus on the discovery potential of the early data, and show the first results
