Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon
Author(s)Counts, Ian Thomas Hunt; Ilten, Philip James; Williams, M.; LHCb collaboration
Precision Measurement of the Mass and Lifetime of the Ξ0b Baryon
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Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb[superscript −1] collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 Ξ0b→Ξ+cπ−, Ξ+c→pK−π+ signal decays are reconstructed. From this sample, the first measurement of the Ξ0b baryon lifetime is made, relative to that of the Λ0b baryon. The mass differences M(Ξ0b)−M(Λ0b) and M(Ξ+c)−M(Λ+c) are also measured with precision more than 4 times better than the current world averages. The resulting values are τΞ0bτΛ0b=1.006±0.018±0.010,M(Ξ0b)−M(Λ0b)=172.44±0.39±0.17 MeV/c2,M(Ξ+c)−M(Λ+c)=181.51±0.14±0.10 MeV/c2, where the first uncertainty is statistical and the second is systematic. The relative rate of Ξ0b to Λ0b baryon production is measured to be fΞ0bfΛ0bB(Ξ0b→Ξ+cπ−)B(Λ0b→Λ+cπ−)B(Ξ+c→pK−π+)B(Λ+c→pK−π+)=(1.88±0.04±0.03)×10−2, where the first factor is the ratio of fragmentation fractions, b→Ξ0b relative to b→Λ0b. Relative production rates as functions of transverse momentum and pseudorapidity are also presented.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review Letters
American Physical Society
Aaij, R., B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, et al. “Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon.” Physical Review Letters 113, no. 3 (July 2014).
Final published version