Author/Authors :
DELPHI Collaboration، نويسنده , , P. Abreu، نويسنده , , W. Adam، نويسنده , , T. Adye، نويسنده , , P. Adzic، نويسنده , , Z. Albrecht، نويسنده , , T. Alderweireld، نويسنده , , G.D. Alekseev، نويسنده , , R. Alemany، نويسنده , , T. Allmendinger، نويسنده , , P.P. Allport، نويسنده , , S. Almehed، نويسنده , , U. Amaldi، نويسنده , , N. Amapane، نويسنده , , S. Amato، نويسنده , , E.G Anassontzis، نويسنده , , P. Andersson، نويسنده , , A. Andreazza، نويسنده , , S. Andringa، نويسنده , , P. Antilogus، نويسنده , , et al.، نويسنده ,
Abstract :
The ratio of the CKM quark-mixing matrix elements |Vub|/|Vcb| has been measured using B hadron semileptonic decays. The analysis uses the reconstructed mass MX of the secondary hadronic system produced in association with an identified lepton. Since B→Xuℓν̄ transitions are characterised by hadronic masses below those of the D mesons produced in B→Xcℓν̄ transitions, events with a reconstructed value of MX significantly below the D mass are selected. Further signal enrichments are obtained using the topology of reconstructed decays and hadron identification. A fit to the numbers of decays in the b→u enriched and depleted samples with MX above and below 1.6 GeV/c2 and to the shapes of the lepton energy distribution in the B rest frame gives |Vub|/|Vcb|=0.103+0.011−0.012 (stat.)±0.016 (syst.)±0.010 (model) and, correspondingly, a charmless semileptonic B decay branching fraction of BR(B→Xuℓν̄)=(1.57±0.35 (stat.)±0.48 (syst.)±0.27 (model))×10−3.
