(B\)-flavor tagging at Belle II

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 \(\Upsilon\)(4\(S\)) resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be \(\varepsilon_{\rm eff} = \big(30.0 \pm 1.2(\text{stat}) \pm 0.4(\text{syst})\big)\%\) for a category-based algorithm and \(\varepsilon_{\rm eff} = \big(28.8 \pm 1.2(\text{stat}) \pm 0.4(\text{syst})\big)\%\) for a deep-learning-based algorithm.