Charm lifetime measurements at Belle II

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 $Λ_c^+$ 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.