Mass and lifetime measurements of bottom and charm baryons in p¯p collisions at √s=1.96 TeV

Abstract

We report on mass and lifetime measurements of several ground state charmed and bottom baryons, using a data sample corresponding to 9.6 fb−1 from p¯p collisions at √s=1.96 TeV and recorded with the Collider Detector at Fermilab. Baryon candidates are reconstructed from data collected with an online event selection designed for the collection of long-lifetime heavy-flavor decay products and a second event selection designed to collect J/ψ→μ+μ− candidates. First evidence for the process Ω−b→Ω0cπ− is presented with a significance of 3.3σ . We measure the following baryon masses:

M(Ξ0c)=2470.85±0.24(stat)±0.55(syst) MeV/c2, M(Ξ+c)=2468.00±0.18(stat)±0.51(syst) MeV/c2, M(Λb)=5620.15±0.31(stat)±0.47(syst) MeV/c2, M(Ξ−b)=5793.4±1.8(stat)±0.7(syst) MeV/c2, M(Ξ0b)=5788.7±4.3(stat)±1.4(syst) MeV/c2, and M(Ω−b)=6047.5±3.8(stat)±0.6(syst) MeV/c2.

The isospin splitting of the Ξ−,0b states is found to be M(Ξ−b)−M(Ξ0b)=4.7±4.7(stat)±0.7(syst) MeV/c2 . The isospin splitting of the Ξ0,+c states is found to be M(Ξ0c)−M(Ξ+c)=2.85±0.30(stat)±0.04(syst) MeV/c2 . The following lifetime measurements are made:

τ(Λb)=1.565±0.035(stat)±0.020(syst) ps, τ(Ξ−b)=1.32±0.14(stat)±0.02(syst) ps, τ(Ω−b)=1.66+0.53−0.40(stat)±0.02(syst) ps.