Date of Original Version

4-17-2008

Type

Article

Abstract or Description

This paper describes the first measurement of b-quark fragmentation fractions into bottom hadrons in Run II of the Tevatron Collider at Fermilab. The result is based on a 360  pb-1 sample of data collected with the CDF II detector in pp̅ collisions at √s=1.96  TeV. Semileptonic decays of B̅ 0, B-, and B̅ s0 mesons, as well as Λb0 baryons, are reconstructed. For an effective bottom hadron pT threshold of 7  GeV/c, the fragmentation fractions are measured to be fu/fd=1.054±0.018(stat)-0.045+0.025(sys)±0.058(B), fs/(fu+fd)=0.160±0.005(stat)-0.010+0.011(sys)-0.034+0.057(B), and fΛb/(fu+fd)=0.281±0.012(stat)-0.056+0.058(sys)-0.087+0.128(B), where the uncertainty B is due to uncertainties on measured branching ratios. The value of fs/(fu+fd) agrees within one standard deviation with previous CDF measurements and the world average of this quantity, which is dominated by LEP measurements. However, the ratio fΛb/(fu+fd) is approximately twice the value previously measured at LEP. The approximately 2σ discrepancy is examined in terms of kinematic differences between the two production environments.

DOI

10.1103/PhysRevD.77.072003

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Published In

Phys. Rev. D , 77, 072003.