Charm and $B$ to charm decays at Belle II

Abstract

We report on precise measurements of charmed hadron lifetimes from the Belle II experiment and on the measurement of the angle ${\hat{I}}^3$ combining Belle and Belle II data. To measure charmed hadron lifetimes we use samples of electron-positron collisions collected from 2019 to 2021 near the $\hat{I}\yen (4S)$ resonance, corresponding to integrated luminosities of up to 207.2 $\mathrm{f}{\mathrm{b}}^{-1}$. The results are the world's best determinations, indicating excellent early detector performance. We measure the angle ${\hat{I}}^3$ using a model-independent Dalitz plot analysis combining Belle and Belle II data, with a total sample size of the order of 1 $\mathrm{a}{\mathrm{b}}^{-1}$. This is the first combined analysis, and shows significant improvement with respect to previous $B$-factory determinations.

6 pages, 10 figures, Moriond ElectroWeak 2022