Measurement of the lifetimes of promptly produced $\hat{I}{\text{c◯}}_c^0$ and $\hat{I}{ž}_c^0$ baryons

Abstract

A measurement of the lifetimes of the $\hat{I}{\text{c◯}}_c^0$ and $\hat{I}{ž}_c^0$ baryons is reported using proton-proton collision data at a centre-of-mass energy of $13\text{ TeV}$, corresponding to an integrated luminosity of $5.4{\text{ fb}}^{-1}$ collected by the LHCb experiment. The $\hat{I}{\text{c◯}}_c^0$ and $\hat{I}{ž}_c^0$ baryons are produced directly from proton interactions and reconstructed in the $p{K}^{-}{K}^{-}\ddot{I}{€}^{+}$ final state. The $\hat{I}{\text{c◯}}_c^0$ lifetime is measured to be $276.5\pm 13.4\pm 4.4\pm 0.7\text{ fs}$, and the $\hat{I}{ž}_c^0$ lifetime is measured to be $148.0\pm 2.3\pm 2.2\pm 0.2\text{ fs}$, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the $D^0$ lifetime. These results confirm previous LHCb measurements based on semileptonic beauty-hadron decays, which disagree with earlier results of a four times shorter $\hat{I}{\text{c◯}}_c^0$ lifetime, and provide the single most precise measurement of the $\hat{I}{\text{c◯}}_c^0$ lifetime.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-021.html (LHCb public pages)