Measurement of the Relative Fragmentation Fractions of B-bar Hadrons
Measurement of the Relative Fragmentation Fractions of B-bar Hadrons

Author: Karen Ruth Gibson

Publisher:

Published: 2006

Total Pages: 169

ISBN-13:

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This thesis describes the first Run II measurement of b quark fragmentation into {bar B}{sup 0}, B{sup -}, and {bar B}{sub s}{sup 0} mesons and {Lambda}{sub b}{sup 0} baryons using semileptonic B decays. The result is based on 360 pb{sup -1} of data collected with the CDF detector in p{bar p} collisions at {radical}s = 1,960 GeV at the Tevatron Collider at Fermilab. The fragmentation fractions are measured for an effective {bar B} hadron p{sub T} threshold of 7 GeV/c to be f{sub u}/f{sub d} = 1.054 {+-} 0.018(stat){sub -0.045}{sup +0.025}(syst) {+-} 0.058(BR), f{sub s}/(f{sub u} + f{sub d}) = 0.160 {+-} 0.005(stat){sub -0.010}{sup +0.011}(syst){sub -0.034}{sup +0.057}(BR), and f{sub {Lambda}{sub b}}/(f{sub u} + f{sub d}) = 0.281 {+-} 0.012(stat){sub -0.056}{sup +0.058}(syst){sub -0.086}{sup +0.128}(BR). f{sub s}/(f{sub u} + f{sub d}) agrees both with previous CDF measurements and the world averages, dominated by the LEP measurements, with {approx} 1{sigma}. However, f{sub {Lambda}{sub b}}/(f{sub u} + f{sub d}) is approximately twice the value which has been measured at LEP and in CDF Run I and disagrees with the LEP results by approximately 2 {sigma}.

Relative Transverse Momentum Distributions of Bottom Hadrons Produced in 1.96 TeV Proton-antiproton Collisions
Relative Transverse Momentum Distributions of Bottom Hadrons Produced in 1.96 TeV Proton-antiproton Collisions

Author:

Publisher:

Published: 2008

Total Pages: 109

ISBN-13:

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Fragmentation is the process by which bare quarks dress themselves up as hadrons. Since we cannot get reliable calculations of this process using perturbative quantum chromodynamics, the fragmentation properties of quarks must be obtained empirically. We report on the signal extraction and relative transverse momentum p{sub T} spectrum determination that will lead to a high precision measurement of relative fragmentation fractions of b quarks into B hadrons, in 1.96 TeV p{bar p} collisions. Using 1.9 fb−1 of data taken with the CDF-II detector, we fully reconstruct 473 ± 42 B{sub s}° → D{sub s}−?, 15206 ± 203 B° → D−?+, 1483 ± 45 B° → D*−?+ and 4444 ± 297?{sub b}° →?{sub c}+?− candidate decays. In order to reduce systematic uncertainties, ratios of p{sub T} spectra are reported. We find that B{sub s} and B° mesons are produced with similar p{sub T} and?{sub b} baryons are produced with lower p{sub T} than B° mesons. Our results are consistent with previous CDF measurements suggesting a difference between fragmentation processes observed at lepton and hadron colliders.

Measurement of the Doubly Inclusive B-bbar Quark Fragmentation Function in Z0 Decays and First Measurement of Angle Dependent B-Bbar Energy Correlation
Measurement of the Doubly Inclusive B-bbar Quark Fragmentation Function in Z0 Decays and First Measurement of Angle Dependent B-Bbar Energy Correlation

Author:

Publisher:

Published: 2002

Total Pages: 5

ISBN-13:

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We present preliminary results of a measurement of the double-inclusive b quark fragmentation function in Z° decays using a novel kinematic B hadron energy reconstruction technique. The measurement is performed using 350,000 hadronic Z° events recorded in the SLD experiment at SLAC between 1996 and 1998. The small and stable SLC beam spot and the CCD-based vertex detector are used to reconstruct topological B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used in this technique. We measure the B energy with good efficiency and resolution over the full kinematic range. We present a preliminary measurement of the angle dependent correlations between the B and {bar B} hadron energies in Z° b{bar b} events, and compare with the leading order QCD predictions.

Hadron Collider Physics - Proceedings Of The Xi Symposium
Hadron Collider Physics - Proceedings Of The Xi Symposium

Author: D Bisello

Publisher: World Scientific

Published: 1997-06-01

Total Pages: 814

ISBN-13: 9814547026

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The proceedings of this series of annual symposia represent an extensive summary of the experimental and theoretical status of high energy physics at hadron colliders. This volume discusses the latest results on top and beauty physics, QCD, electroweak physics and searches for new particles. The prospects of this field for LHC, Tevatron and Hera machines are also reported.

Measurement of the Branching Fractions of Bbar -] D** L^- Nubar_l Decays in Events Tagged by a Fully Reconstructed B Meson
Measurement of the Branching Fractions of Bbar -] D** L^- Nubar_l Decays in Events Tagged by a Fully Reconstructed B Meson

Author:

Publisher:

Published: 2008

Total Pages: 7

ISBN-13:

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We report a measurement of the branching fractions of {bar B} 2!D** l−{bar {nu}}{sub l} decays based on 417 fb−1 of data collected at the [Upsilon](4S) resonance with the BABAR detector at the PEP-II ee− storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D{sup (*)})-m(D{sup (*)}) is performed to extract the signal yields of the different D** states. We observe the {bar B} 2!D**{ell}−{bar {nu}}{sub {ell}} decay modes corresponding to the four D** states predicted by Heavy Quark Symmetry with a significance greater than six standard deviations including systematic uncertainties.