Measurement of the ${\mathrm{\Omega }}_c^0$ and ${\mathrm{\Xi }}_c^0$ baryon lifetimes using hadronic $b$-baryon decays

The lifetimes of the ${\mathrm{\Omega }}_c^0$ and ${\mathrm{\Xi }}_c^0$ baryons are measured using a $pp$ collision dataset collected by the LHCb experiment, corresponding to an integrated luminosity of $9\mathrm{f}{\mathrm{b}}^{-1}$. The charm baryons are produced in the fully reconstructed decay chains ${\mathrm{\Omega }}_b^{-}\to {\mathrm{\Omega }}_c^0(\to p{K}^{-}{K}^{-}{\pi }^{+}){\pi }^{-}$ and ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}_c^0(\to p{K}^{-}{K}^{-}{\pi }^{+}){\pi }^{-}$. The measurement uses topologically and kinematically similar $B^{-}\to D^0(\to K^{-}{K}^{+}{\pi }^{-}{\pi }^{+}){\pi }^{-}$ decays for normalisation. The measured lifetimes are ${\tau }_{{\mathrm{\Omega }}_c^0}=276.3\pm 19.4(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 1.8(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\pm 0.7({\tau }_{D^0})\mathrm{f}\mathrm{s}$, ${\tau }_{{\mathrm{\Xi }}_c^0}=149.2\pm 2.5(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 0.9(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\pm 0.4({\tau }_{D^0})\mathrm{f}\mathrm{s}$, where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the $D^0$ lifetime. These results are consistent with previous measurements performed by the LHCb experiment.