Measurement of Ratios of Fragmentation Fractions for Bottom Hadrons in p-pbar Collisions at sqrts=1.96 TeV
Abstract
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 p-pbar collisions at sqrts=1.96 TeV. Semileptonic decays of B0, B+, and Bs mesons, as well as Lambdab 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) +0.025-0.045(sys) +/- 0.058 (Br), fs/(fu+fd)=0.160 +/- 0.005 (stat) +0.011-0.010 (sys) +0.057-0.034 (Br), and fLambdab/(fu+fd)=0.2810.012 (stat) +0.058-0.056 (sys) +0.128-0.086 (Br), where the uncertainty (Br) 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 fLambdab/(fu+fd) is approximately twice the value previously measured at LEP. The approximately 2 sigma discrepancy is examined in terms of kinematic differences between the two production environments.