Yun-Tsung Lai

02 December 2020

Abstract: We report on first measurement of branching fractions ($\mathcal{B}$) and $CP$ asymmetries ($\mathcal{A}$) in various charmless $B$ decays at Belle II. We utilize a data sample of 34.6 fb$^{-1}$ which is collected in SuperKEKB $e^{+}e^{-}$ collider at the $\Upsilon$(4S) resonance in 2019 and 2020. The analysis procedures, including the Monte Carlo (MC) simulation study, background reduction, and physics observable measurements, will be described in detail in this report. Polarization fraction of $B\to\phi K^{*}$ modes is also measured. All these results in charmless $B$ decays from Belle II are consistent with world average and are good validations on the detector systems and analysis strategies. Belle II is ready for more new physics search with larger data set in near future in all aspects.