Measurement of the $B^0$ lifetime using fully reconstructed hadronic decays in the 2019 Belle II dataset

Abstract

This document presents the measurement of $B^0$ meson lifetimes using the 2019 Belle II dataset that corresponds to an integrated luminosity of $8.7\pm 0.2$ fb${}^{-1}$. Each candidate is fully reconstructed with hadronic decay final states on the signal side, while the rest-of-event technique allows to infer the decay vertex position on the other (tag) side. $B^0$ lifetime is extracted from an unbinned maximum likelihood fit to the distribution of the difference between the signal side $B^0$ candidate and the tag side decay times. The measured lifetime is $\ddot{I}{„}_{B^0}=1.48\pm 0.28\pm 0.06$ ps, where the first uncertainty is statistical and the second is systematic.

16 pages, 5 figures