TY - JOUR

T1 - Measurements of inclusive semileptonic branching fractions of b hadrons in Z0 decays

AU - Kartvelishvili, Vakhtang

AU - OPAL Collaboration

PY - 2000/3

Y1 - 2000/3

N2 - A measurement of inclusive semileptonic branching fractions of b hadrons produced in Z0 decays is presented. An enriched Z0→bb¯ sample is obtained with a lifetime flavour-tagging technique. The leptonic events are then selected from this sample, and classified according to their origin, which is determined by comparing the distribution of several kinematic variables using artificial neural network techniques. Using 3.6 million multihadronic events collected with the OPAL detector at energies near the Z0 resonance, the valuesBR(b → ℓX) = (10.84 ± 0.09 (stat.) ± 0.21 (syst.) +0.21−0.13 (model))BR(b → c → ℓX) = ( 8.39 ± 0.15 (stat.) ± 0.22 (syst.) +0.33−0.29 (model)).are measured, where b denotes all weakly decaying b hadrons and ℓ represents either e or μ. The second error includes all experimental systematic uncertainties whereas the last error is due to uncertainties in modelling of the lepton momentum spectrum in semileptonic decays and b quark fragmentation. The average fraction of the beam energy carried by the weakly decaying b hadron, ⟨xE⟩, is measured to be(xE) = 0.709 ± 0.003 (stat.) ± 0.003 (syst.) ± 0.013 (model)where the modelling error is dominated by the choice of b fragmentation model. The agreement between data and various semileptonic decay models and fragmentation functions is also investigated.

AB - A measurement of inclusive semileptonic branching fractions of b hadrons produced in Z0 decays is presented. An enriched Z0→bb¯ sample is obtained with a lifetime flavour-tagging technique. The leptonic events are then selected from this sample, and classified according to their origin, which is determined by comparing the distribution of several kinematic variables using artificial neural network techniques. Using 3.6 million multihadronic events collected with the OPAL detector at energies near the Z0 resonance, the valuesBR(b → ℓX) = (10.84 ± 0.09 (stat.) ± 0.21 (syst.) +0.21−0.13 (model))BR(b → c → ℓX) = ( 8.39 ± 0.15 (stat.) ± 0.22 (syst.) +0.33−0.29 (model)).are measured, where b denotes all weakly decaying b hadrons and ℓ represents either e or μ. The second error includes all experimental systematic uncertainties whereas the last error is due to uncertainties in modelling of the lepton momentum spectrum in semileptonic decays and b quark fragmentation. The average fraction of the beam energy carried by the weakly decaying b hadron, ⟨xE⟩, is measured to be(xE) = 0.709 ± 0.003 (stat.) ± 0.003 (syst.) ± 0.013 (model)where the modelling error is dominated by the choice of b fragmentation model. The agreement between data and various semileptonic decay models and fragmentation functions is also investigated.

U2 - 10.1007/s100520000323

DO - 10.1007/s100520000323

M3 - Journal article

VL - 13

SP - 225

EP - 240

JO - European Physical Journal C: Particles and Fields

JF - European Physical Journal C: Particles and Fields

SN - 1434-6044

IS - 2

ER -