Lancaster, M; Malik, S; Nurse, EL; Waters, DCDFC; (2008) Measurement of ratios of fragmentation fractions for bottom hadrons in pp̅ collisions at sqrt[s] =1.96  TeV. Physical Review D , 77 (7) , Article 072003. 10.1103/PhysRevD.77.072003.

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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 ¯ p collisions at √ s = 1.96     TeV . Semileptonic decays of ¯¯¯ B 0 , B − , and ¯¯¯ B 0 s mesons, as well as Λ 0 b baryons, are reconstructed. For an effective bottom hadron p T threshold of 7     GeV / c , the fragmentation fractions are measured to be f u / f d = 1.054 ± 0.018 ( stat ) + 0.025 − 0.045 ( sys ) ± 0.058 ( B ) , f s / ( f u + f d ) = 0.160 ± 0.005 ( stat ) + 0.011 − 0.010 ( sys ) + 0.057 − 0.034 ( B ) , and f Λ b / ( f u + f d ) = 0.281 ± 0.012 ( stat ) + 0.058 − 0.056 ( sys ) + 0.128 − 0.087 ( B ) , where the uncertainty B is due to uncertainties on measured branching ratios. The value of f s / ( f u + f d ) 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 f Λ b / ( f u + f d ) is approximately twice the value previously measured at LEP. The approximately 2 σ discrepancy is examined in terms of kinematic differences between the two production environments.

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