Precision measurement of the ratio of the Lambda(0)(b) to (B)over-bar(0) lifetimes

The LHCb measurement of the lifetime ratio of the Λ 0 b baryon to the B0 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 Λ 0 b → J/ψ pK− and B0 → J/ψ π+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 B0 lifetime, the Λ 0 b lifetime is found to be 1.479 ± 0.009 ± 0.010 ps