We report on measurements of the mass and lifetime of the Ξ - b baryon using about 1800 Ξ - b decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0 fb -1, collected by the LHCb experiment. The decays are reconstructed in the Ξ - b → Ξ 0 cπ -, Ξ 0 c → pK -K -π +, channel and the mass and lifetime are measured using the Λ 0 b → Λ + Cπ -, mode as a reference. We measure M (Ξ - b) - M(Λ 0 b)= 178.36 ± 0.46 ± 0.16 MeV=c 2, (τξ - B/τΛ 0 b) = 1.089 ± 0.026 ± 0.011, where the uncertainties are statistical and systematic, respectively. These results lead to a factor of 2 better precision on the Ξ - b mass and lifetime compared to previous best measurements, and are consistent with theoretical expectations.
All Science Journal Classification (ASJC) codes
- Física y astronomía (todo)