Precision measurement of the $\Xi_b^0$ baryon lifetime

A sample of pp collision data, corresponding to an integrated luminosity of 5.4 fb−1 and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the Ξb0 baryon to that of the Λb0 baryon, rτ≡τΞb0/τΛb0. The value rτRun 2=1.004±0.009±0.006 is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain rτ=1.004±0.008±0.005. Multiplying by the known value of the Λb0 lifetime yields τΞb0=1.475±0.012±0.008±0.009 ps, where the last uncertainty is due to the limited knowledge of the Λb0 lifetime. This measurement improves the precision of the current world average of the Ξb0 lifetime by about a factor of two, and is in good agreement with the most recent theoretical predictions.