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Abstract
The LHCb measurement of the lifetime ratio of the Λb0 baryon to the B¯0 meson is updated using data corresponding to an integrated luminosity of 3.0 fb−1 collected using 7 and 8 TeV centre-of-mass energy pp collisions at the LHC. The decay modes used are Λb0→J/ψpK− and B¯0→J/ψπ+K−, where the π+K− mass is consistent with that of the K¯⁎0(892) meson. The lifetime ratio is determined with unprecedented precision to be 0.974±0.006±0.004, where the first uncertainty is statistical and the second systematic. This result is in agreement with original theoretical predictions based on the heavy quark expansion. Using the current world average of the B¯0 lifetime, the Λb0 lifetime is found to be 1.479±0.009±0.010 ps.
Highlights
The heavy quark expansion (HQE) is a powerful theoretical technique in the description of decays of hadrons containing heavy quarks
Event selection and b hadron reconstruction. Events selected for this analysis are triggered by a J /ψ → μ+μ− decay, where the J /ψ is required at the software level to be consistent with coming from the decay of a b hadron by use of either impact parameter (IP) requirements or detachment of the reconstructed J /ψ decay position from the associated primary vertex
We determine the ratio of lifetimes of the Λb0 baryon and B0 meson to be τΛb0 = 0.974 ± 0.006 ± 0.004. τB0
Summary
The heavy quark expansion (HQE) is a powerful theoretical technique in the description of decays of hadrons containing heavy quarks. For b-flavored hadrons, the expansion of the total decay width in terms of powers of 1/mb, where mb is the b quark mass, was derived a few years later [3]. The most precise previous measurement from LHCb, 0.976 ± 0.012 ± 0.006 [14], based on 1.0 fb−1 of data, agreed with the early HQE expectations. In this data from paper we 3.0 fb−1 present an updated result for τΛb0 /τB0 using of integrated luminosity collected with the LHCb detector from pp collisions at the LHC. The trigger [19] consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which applies a full event reconstruction
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