Precision measurement of the ${\hat{I}ž}_b^0$ baryon lifetime

Abstract

A sample of $pp$ collision data, corresponding to an integrated luminosity of 5.4 fb${}^{-1}$ and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the ${\hat{I}ž}_b^0$ baryon to that of the ${\hat{I}›}_b^0$ baryon, $r_{\ddot{I}}„\equiv \ddot{I}{„}_{{\hat{I}ž}_b^0}/\ddot{I}{„}_{{\hat{I}›}_b^0}$. The value $r_{\ddot{I}}{„}^{\mathrm{Run}2}=1.004\pm 0.009\pm 0.006$ is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain $r_{\ddot{I}}„=1.004\pm 0.008\pm 0.005$. Multiplying by the known value of the ${\hat{I}›}_b^0$ lifetime yields $\ddot{I}{„}_{{\hat{I}ž}_b^0}=1.475\pm 0.012\pm 0.008\pm 0.009\mathrm{ps}$, where the last uncertainty is due to the limited knowledge of the ${\hat{I}›}_b^0$ lifetime. This measurement improves the precision of the current world average of the ${\hat{I}ž}_b^0$ lifetime by about a factor of two, and is in good agreement with the most recent theoretical predictions.

12 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/4483 (LHCb public pages)