Charm lifetime measurements at Belle II

TL;DR

Belle II's early data has enabled precise charm hadron lifetime measurements, refining existing values and testing models related to non-perturbative effects, crucial for understanding potential physics beyond the standard model.

Contribution

First measurements of charm hadron lifetimes at Belle II with improved precision, serving as benchmarks and testing effective models for non-perturbative effects.

Findings

Measured $D^+$, $D^0$, and $\\Lambda_c^+$ lifetimes consistent with previous results

Enhanced precision of charm hadron lifetime measurements

Results will refine world averages and test theoretical models

Abstract

Upgrades at the Belle II experiment and the SuperKEKB asymmetric-energy electron-positron collider enable precise measurements of particle decays. Even with early data, Belle II has made several world-leading measurements of particle lifetimes, which are useful as tests of effective models used in searches for physics beyond the standard model. Especially for charm hadrons, these effective models depend on careful consideration of non-perturbative effects to give an adequate description of lifetimes. Recent measurements at other experiments have stimulated particular interest in charm baryons, including several measurements that indicate the hierarchy of lifetimes is different than once believed. The measurements of the $D^+$, $D^0$, and $\Lambda_c^+$ lifetimes at Belle II are consistent with previous measurements, but with improved precision. These measurements will improve the world-average values, provide refined tests for effective models, and serve as benchmarks for future measurements.