Measurement of the Lambda_b lifetime and mass in the ATLAS experiment

Abstract

A measurement of the Lambda_b lifetime and mass in the decay channel Lambda_b -> J/psi(mu^+ mu^-) Lambda^0(p pi^-) is presented. The analysis uses a signal sample of about 2200 Lambda_b and anti-Lambda_b decays that are reconstructed in 4.9 fb^-1 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 Lambda_b lifetime and mass. They are measured to be tau(Lambda_b) = 1.449 +/- 0.036(stat) +/- 0.017(syst) ps and m(Lambda_b) = 5619.7 +/- 0.7(stat) +/- 1.1(syst) MeV.

7 pages plus author list (20 pages total), 3 figures, 2 tables, submitted to Physical Review D. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2012-03/

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• Measurement of the Lambda_b^0 lifetime in the exclusive decay Lambda_b^0 -> J/psi Lambda^0 in ppbar collisions at sqrt(s)=1.96 TeV

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