# Charm and $B$ to charm decays at Belle II

## TL;DR

This paper presents the Belle II experiment's precise measurements of charmed hadron lifetimes and the angle gamma, demonstrating early detector performance and improved combined analysis results compared to previous studies.

## Contribution

First combined analysis of Belle and Belle II data for charmed hadron lifetimes and the angle gamma, showing significant improvements over previous measurements.

## Key findings

- World's best determinations of charmed hadron lifetimes.
- First combined analysis of Belle and Belle II data for gamma angle.
- Significant improvement over previous B-factory results.

## Abstract

We report on precise measurements of charmed hadron lifetimes from the Belle II experiment and on the measurement of the angle $\gamma$ 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 $\Upsilon(4S)$ resonance, corresponding to integrated luminosities of up to 207.2 ${\rm fb^{-1}}$. The results are the world's best determinations, indicating excellent early detector performance. We measure the angle $\gamma$ using a model-independent Dalitz plot analysis combining Belle and Belle II data, with a total sample size of the order of 1 ${\rm ab^{-1}}$. This is the first combined analysis, and shows significant improvement with respect to previous $B$-factory determinations.