Precision measurement of the mass and lifetime of the Ξb0 baryon

Using a proton-proton collision data sample corresponding to an integrated luminosity of 3fb-1 collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 Ξb0→Ξc+π-, Ξc+→pK-π+ signal decays are reconstructed. From this sample, the first measurement of the Ξb0 baryon lifetime is made, relative to that of the Λb0 baryon. The mass differences M(Ξb0)-M(Λb0) and M(Ξc+)-M(Λc+) are also measured with precision more than 4 times better than the current world averages. The resulting values are τΞb0τΛb0=1.006±0. 018±0.010,M(Ξb0)-M(Λb0)=172.44±0.39±0.17MeV/c2, M(Ξc+)-M(Λc+)=181.51±0.14±0.10MeV/c2,where the first uncertainty is statistical and the second is systematic. The relative rate of Ξb0 to Λb0 baryon production is measured to be fΞb0fΛ b0B(Ξb0→Ξc+π-)B(Λb0→Λc+π-) B(Ξc+→pK-π+)B(Λc+→pK-π+)=(1.88±0.04±0. 03)×10-2,where the first factor is the ratio of fragmentation fractions, b→Ξb0 relative to b→Λb0. Relative production rates as functions of transverse momentum and pseudorapidity are also presented. © 2014 CERN, for the LHCb Collaboration.