Determination of [verticalV[sub Ub][vertical in Inclusive Semileptonic B Meson Decays
Determination of [verticalV[sub Ub][vertical in Inclusive Semileptonic B Meson Decays

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Published: 2004

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The authors present a preliminary determination of the CKM matrix element V[sub ub] based on the analysis of semileptonic B decays from a sample of 88 million [Upsilon](4S) decays collected with the BaBar detector at the e[sup +]e[sup -] storage ring. Charmless semileptonic B decays are selected using the electron energy E-e and the invariant mass q[sup 2] of the electron-neutrino pair. The neutrino meomentum is inferred from a measurement of the visible energy and momentum in the detector and knowledge of the e[sup +]e[sup -] beam momenta. The partial branching fraction is determined in a region of the q[sup 2]-E-e plane where semileptonic B decays to charm are highly suppressed. The total charmless semileptonic branching fraction is extracted using a theoretical calculation based on the heavy quark expansion. Preliminary results yield V[sub ub] = (4.57 [+-] 0.21 [+-] 0.25 [+-] 0.34 + 0.59 - 0.29 [+-] 0.22) x 10[sup -3] where the uncertainties are from statistics (data and MC), detector modeling, background modeling, the shape function, and the heavy quark operator product expansion, respectively.

Inclusive Semileptonic B Decays at BABAR.
Inclusive Semileptonic B Decays at BABAR.

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Published: 2004

Total Pages:

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The authors report updates on two analyses of inclusive semileptonic B decays based on a dataset of 89 million B[bar B] events recorded with the BABAR detector at the [Upsilon](4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other [bar B] meson. IN the first analysis, the measurement of the first and second moment of the hadronic mass distribution in Cabibbo-favored [bar B] [yields] X[sub c][ell][bar [nu]] decays allows for the determination of the nonperturbative parameters [bar [Lambda]] and [lambda][sub 1] of Heavy Quark Effective Theory (HQET) and V[sub cb]. In the second analysis, the hadronic mass distribution is used to measure the inclusive charmless semileptonic branching fraction and to determine V[sub ub].