Measurement of the Λ<SUP>0</SUP><SUB>b</SUB> lifetime and mass in the ATLAS experiment

Abstract

A measurement of the Λ<SUP>0</SUP><SUB>b</SUB> lifetime and mass in the decay channel Λ<SUP>0</SUP><SUB>b</SUB> →J/ψ(μ<SUP>+</SUP>μ¯)Λ<SUP>0</SUP>(pπ¯) is presented. The analysis uses a signal sample of about 2200 Λ<SUP>0</SUP><SUB>b</SUB> and Λ¯<SUP>0</SUP><SUB>b</SUB> decays that are reconstructed in 4.9 fb<SUP>-1</SUP> of ATLAS pp collision data collected in 2011 at the LHC center-of-mass energy of 7 TeV. A simultaneous mass and decay time maximum likelihood fit is used to extract the Λ<SUP>0</SUP><SUB>b</SUB> lifetime and mass. They are measured to be τ<SUB>Λ_b</SUB>=1.449±0.036(stat) ±0.017(syst) ps and m<SUB>Λ_b</SUB>=5619.7±0. 7(stat)±1.1(syst) MeV.