Determination of |Vub|/|Vcb| with DELPHI at LEP

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 M_X of the secondary hadronic system produced in association with an identified lepton. Since B -> X_u lepton anti-nu transitions are characterised by hadronic masses below those of the D mesons produced in B -> X_c lepton anti-nu transitions, events with a reconstructed value of M_X 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 M_X above and below 1.6 GeV/c^2 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 -> X_u lepton anti-nu) = (1.57 +/- 0.35 (stat.) +/- 0.48 (syst.) +/- 0.27 (model)) x 10^{-3}.

24 pages, 8 figures

References in corpus (4)

• The bottom $\overline{\mathrm{MS}}$ quark mass from sum rules at next-to-next-to-leading order
• Measurement of $B\to \rho \ell \nu$ Decay and $|V_{ub}|$
• Theoretical Uncertainties in Gamma_sl(b->u)
• Combined results on b-hadron production rates, lifetimes, oscillations and semileptonic decays

Cited by in corpus (14)

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• Measurement of the inclusive electron spectrum from B meson decays and determination of |Vub|
• On The Expected Photon Spectrum in B -> X_s + gamma and Its Uses
• Subleading shape function contributions to the hadronic invariant mass spectrum in B -> X_u l νdecay
• Measurement of |V_{ub}/V_{cb}| (and |V_{ub}|) in Exclusive Nonleptonic Decays, \bar{B}^0 --> D_s^{(*)-}(π^+,ρ^+) and \bar{B}^0 --> D_s^{(*)-}D^{(*)+}
• A new model-independent way of extracting |V_ub/V_cb|
• Experimental Status of Semileptonic B Decays - Recent Results from LEP and Comparisons with Y(4S) Experiments
• B Physics at the Z0 Resonance
• Flavor Physics and the CKM Matrix: An Overview
• Determinations of |Vub| with inclusive techniques at LEP