B-flavor tagging at Belle II

Sumitted to PubDB: 2022-04-03

Category: Technical Paper, Visibility: Public

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Authors	Fernando Abudinen, Takeo Higuchi, Colm Murphy
Date	Sept. 14, 2021
Belle II Number	BELLE2-PUB-TE-2021-002
Abstract	We report on new flavor-tagging algorithms developed to determine the quark-flavor content of bottom (B) mesons at Belle II. The algorithms provide essential inputs for measurements of quark-flavor mixing and charge-parity violation. We validate and evaluate the performance of the algorithms using hadronic B decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb$^{-1}$, collected at the Y(4S) resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be $\varepsilon_{\rm eff} = (30.0 \pm 1.2(stat) \pm 0.4(syst))\%$ for a category-based algorithm and $\varepsilon_{\rm eff} = (28.8 \pm 1.2(stat) \pm 0.4(syst))\%$ for a deep-learning-based algorithm.