Mass and lifetime measurements of bottom and charm baryons in $p\bar{p}$ collisions at $\sqrt{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 ${\text{fb}}^{-1}$ from $p\bar{p}$ collisions at $\sqrt{s}=1.96$ 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 $J/\ddot{I}ˆ\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ candidates. First evidence for the process $\hat{I}{\text{c◯}}_b^{-}\to \hat{I}{\text{c◯}}_c^0\ddot{I}{€}^{-}$ is presented with a significance of $3.3\ddot{I}ƒ$. We measure the following baryon masses: \begin{eqnarray} M(Ξ_c^{0}) = 2470.85\pm0.24(stat)\pm0.55(syst) \, MeV/c^2, \nonumber M(Ξ_c^{+}) = 2468.00\pm0.18(stat)\pm0.51(syst) \, MeV/c^2, \nonumber \\ M(Λ_b) = 5620.15\pm0.31(stat)\pm0.47(syst) \, MeV/c^2, \nonumber \\ M(Ξ_b^-) = 5793.4\pm1.8(stat)\pm0.7(syst) \, MeV/c^2, \nonumber \\ M(Ξ_b^0) = 5788.7\pm4.3(stat)\pm1.4(syst) \, MeV/c^2, \, and \nonumber \\ M(Ω_b^-) = 6047.5\pm3.8(stat)\pm0.6(syst) \, MeV/c^2. \nonumber \end{eqnarray} The isospin splitting of the $\hat{I}{ž}_b^{-,0}$ states is found to be $M(\hat{I}{ž}_b^{-})-M(\hat{I}{ž}_b^0)=4.7\pm 4.7(stat)\pm 0.7(syst)$ MeV/$c^2$. The isospin splitting of the $\hat{I}{ž}_c^{0,+}$ states is found to be $M(\hat{I}{ž}_c^0)-M(\hat{I}{ž}_c^{+})$ = $2.85\pm 0.30(stat)\pm 0.04(syst)$ MeV/$c^2$. The following lifetime measurements are made: \begin{eqnarray} τ(Λ_b) = 1.565\pm0.035(stat)\pm0.020(syst) \, ps, \nonumber \\ τ(Ξ_b^-) = 1.32\pm0.14(stat)\pm0.02(syst) \, ps, \nonumber \\ τ(Ω_b^-) = 1.66^{+0.53}_{-0.40}(stat)\pm0.02(syst) \, ps. \nonumber \end{eqnarray}