Precision measurement of the Λc+, Ξc+, and Ξc0 baryon lifetimes

Abstract

We report measurements of the lifetimes of the Λþc , Ξþc and Ξ0 c 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 fb−1, collected by the LHCb experiment. The charm baryons are reconstructed through the decays Λþc → pK−πþ, Ξþc → pK−πþ and Ξ0c → pK−K−πþ, and originate from semimuonic decays of beauty baryons. The lifetimes are measured relative to that of the Dþ meson, and are determinedto be τΛþc ¼ 203.51.01.31.4 fs; τΞþc ¼ 456.83.52.93.1 fs; τΞ0 c ¼ 154.51.71.61.0 fs; where the uncertainties are statistical, systematic, and due to the uncertainty in the Dþ lifetime. The measurements are approximately 3-4 times more precise than the current world average values. The Λþc and Ξþ c lifetimes are in agreement with previous measurements; however, the Ξ0 c baryon lifetime is approximately 3.3 standard deviations larger than the world average value.