Volume 377 - 18th International Conference on B-Physics at Frontier Machines (Beauty2019) - Lifetimes
Time-dependent studies with early Belle II data
Y. Yusa
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Pre-published on: 2020 March 19
Published on:
Abstract
After the 2018 commissioning run, in which 0.5 fb$^{-1}$ of data were collected at a center of mass energy corresponding to the mass of the $\Upsilon(4S)$, the construction of the Belle II detector was completed with the installation of a silicon vertex detector that covers most of the solid angle around the interaction region. The first physics run started in the spring of 2019. We utilize this dataset to characterize the performance of the detector about tracking of charged particles, reconstruction of known resonances, and capability of identifying displaced decay vertices.
In order to assess the $B$ physics capabilities of the experiment, one of the first benchmarks to be reached consists in the measurement of the $B^0$-$\bar{B}^0$ mixing frequency. We present the first results, based on samples of $B$ mesons that decay to semileptonic final state. A discovery of the $B^0 \to J/\psi K^0_S$ decay which is one of the $CP$-eigenstates is also reported.
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