Measurement of the Ωc0 baryon lifetime with LHCb

Abstract

The results of the measurement of the Ωc0 charmed baryon lifetime via the Ωb → Ωc0π decay mode are presented in this thesis. The result makes use of the proton-proton collision data collected by the LHCb detector at CERN in the years 2011-2012 and 2015-2016 using the full 8.7 fb⁻¹ total integrated luminosity data. The lifetime of the Ωc0 baryon was measured to be τΩc0 = 238 ± 33 (stat) ± 21 (syst) ± 1 (τD⁰) fs, where the first uncertainty is statistical, the second systematic, and the third due to the use of the world-average D⁰ lifetime. The lifetime is measured as a ratio of Ωb → Ωc0π to B → D⁰π decays in order to cancel out the decay time dependent reconstruction and selection efficiencies, using 284 Ωc0 and 55317 D⁰ candidates. The measurement agrees with the previous LHCb measurement in 2016 [1], at -0.63σ from the measurement, using data collected in 2011-2012 of τΩc0 = 268 ± 24 ± 10 fs, which reorders the hierarchy of the charmed baryon lifetimes predicted in the heavy quark effective theory