Measurement of the 𝛬⁰b lifetime and mass in the ATLAS experiment

A measurement of the 𝛬⁰b lifetime and mass in the decay channel 𝛬⁰_𝑏→𝐽/𝜓⁡(𝜇⁺⁢𝜇^−)⁢𝛬⁰⁡(𝑝⁢𝜋^−) is presented. The analysis uses a signal sample of about 2200 𝛬⁰_𝑏 and 𝛬̄⁰_𝑏 decays that are reconstructed in 4.9 fb⁻¹ of ATLAS $𝑝⁢𝑝$ 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 𝛬⁰_𝑏 lifetime and mass. They are measured to be 𝜏𝛬𝑏=1.449±0.036⁢(stat)±0.017⁢(syst) ps and 𝑚𝛬𝑏=5619.7±0.7⁢(stat)±1.1⁢(syst) MeV.