We report measurements of the lifetimes of the ${\mathrm{\Lambda }}_c^{+}$, ${\mathrm{\Xi }}_c^{+}$ and ${\mathrm{\Xi }}_c^0$ charm baryons using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$, collected by the LHCb experiment. The charm baryons are reconstructed through the decays ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$, ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ and ${\mathrm{\Xi }}_c^0\to p{K}^{-}{K}^{-}{\pi }^{+}$, and originate from semimuonic decays of beauty baryons. The lifetimes are measured relative to that of the $D^{+}$ meson, and are determined to be ${\tau }_{{\mathrm{\Lambda }}_c^{+}}=203.5\pm 1.0\pm 1.3\pm 1.4\mathrm{fs},{\tau }_{{\mathrm{\Xi }}_c^{+}}=456.8\pm 3.5\pm 2.9\pm 3.1\mathrm{fs},{\tau }_{{\mathrm{\Xi }}_c^0}=154.5\pm 1.7\pm 1.6\pm 1.0\mathrm{fs},$ where the uncertainties are statistical, systematic, and due to the uncertainty in the $D^{+}$ lifetime. The measurements are approximately 3–4 times more precise than the current world average values. The ${\mathrm{\Lambda }}_c^{+}$ and ${\mathrm{\Xi }}_c^{+}$ lifetimes are in agreement with previous measurements; however, the ${\mathrm{\Xi }}_c^0$ baryon lifetime is approximately 3.3 standard deviations larger than the world average value.

• Received 19 June 2019

DOI:https://doi.org/10.1103/PhysRevD.100.032001

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© 2019 CERN, for the LHCb Collaboration