Precision measurement of the mass and lifetime of the Ξ0b Baryon

The LHCb Collaboration

Research output: Contribution to journalArticleResearchpeer-review

33 Citations (Scopus)


Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb−1 collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 Ξ0 b → Ξþ c π−, Ξþ c → pK−πþ signal decays are reconstructed. From this sample, the first measurement of the Ξ0 b baryon lifetime is made, relative to that of the Λ0 b baryon. The mass differences MðΞ0 bÞ − MðΛ0 bÞ and MðΞþ c Þ − MðΛþ c Þ are also measured with precision more than 4 times better than the current world averages. The resulting values are
τΞ0bτΛ0b¼ 1.006 0.018 0.010;
MðΞ0bÞ − MðΛ0bÞ ¼ 172.44 0.39 0.17 MeV=c2;
MðΞþc Þ − MðΛþc Þ ¼ 181.51 0.14 0.10 MeV=c2
where the first uncertainty is statistical and the second is systematic. The relative rate of Ξ0 b to Λ0 b baryon production is measured to be
fΞ0bfΛ0bBðΞ0b → Ξþc π−ÞBðΛ0b → Λþc π−ÞBðΞþc → pK−πþÞBðΛþc → pK−πþÞ¼ ð1.88 0.04 0.03Þ × 10−2;
where the first factor is the ratio of fragmentation fractions, b → Ξ0
b relative to b → Λ0b. Relative production rates as functions of transverse momentum and pseudorapidity are also presented.
Original languageEnglish
Article number032001
Number of pages10
JournalPhysical Review Letters
Issue number3
Publication statusPublished - 2014
Externally publishedYes

Cite this