Measurements of Moments of the Hadronic Mass Distribution in Semileptonic B Decays PDF Download
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Languages : en
Pages : 10
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We report a measurement of the first four moments of the hadronic mass distribution in {bar B} → X{sub c}l− {bar {nu}} decays. The measurements are based on 89 million [Upsilon](4S) → B{bar B} events where the hadronic decay of one of the B mesons is fully reconstructed and a charged lepton from the decay of the other B meson is identified. The moments are presented for minimum lepton momenta ranging from 0.9 to 1.6 GeV in the B rest frame. It is expected that such measurements will lead to improved determinations of.
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Languages : en
Pages : 10
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We report a measurement of the first four moments of the hadronic mass distribution in {bar B} → X{sub c}l− {bar {nu}} decays. The measurements are based on 89 million [Upsilon](4S) → B{bar B} events where the hadronic decay of one of the B mesons is fully reconstructed and a charged lepton from the decay of the other B meson is identified. The moments are presented for minimum lepton momenta ranging from 0.9 to 1.6 GeV in the B rest frame. It is expected that such measurements will lead to improved determinations of.
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Languages : en
Pages : 24
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We report a preliminary measurement of the first and second moments of the hadronic mass distributions in B → X{sub c}l[nu] decays. The measurements are based on [Upsilon](4S) → B{bar B} events where the hadronic decay of one of the B mesons is fully reconstructed and a charged lepton from the decay of the other B meson is identified. The moments are presented for threshold lepton momenta ranging from 0.9 to 1.6 GeV. From the M{sub X}2 moments we determine the non-perturbative Heavy Quark Expansion (HQE) parameters, {bar {Lambda}} and [lambda]1. We combine the measured moments M{sub X}2 with earlier BABAR measurements of the semileptonic branching ratios and B lifetimes and perform a simultaneous fit to the HQE for the moments obtained for different threshold lepton momenta and the semileptonic decay width. This fit results in an improved value for the CKM matrix element.
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Languages : en
Pages : 9
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Languages : en
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Using 180 pb−1 of data collected with the CDF II detector at the Tevatron, we measure the first two moments of the hadronic invariant mass-squared distribution in charmed semileptonic B decays. From these we determine the non-perturbative Heavy Quark Effective Theory parameters? and?1 used to relate the B meson semileptonic branching ratio to the CKM matrix element.
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Languages : en
Pages : 159
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This thesis presents first measurements of moments of the hadronic nX2 distribution measured in inclusive semileptonic decays of B mesons to final states containing a charm quark, B 2!Xcl[nu]. The variable nX2 is a combination of the invariant mass of the charmed meson mX, its energy in the B-meson rest-frame EX;BRF, and a constant ~[Lambda] = 0.65 GeV, nX2 = mX2c4-2~[Lambda]EX, BRF + ~[Lambda]2. The moments nXk with k = 2,4,6 are measured as proposed by theory to constrain assumptions made in the theoretical description of inclusive observables in semileptonic B-meson decays. This description uses Heavy Quark Expansion (HQE), an effective QCD combined with an Operator Product Expansion. The measurement is based on a sample of 231.6 million e+e- 2 2!B$\bar{B}$ events recorded with the BABAR experiment at the PEP-II e+e--storage rings at SLAC. We reconstruct the semileptonic decay by identifying a charged lepton in events tagged by a fully reconstructed hadronic decay of the second B meson. Correction procedures are derived from Monte Carlo simulations to ensure an unbiased measurement of the moments of the nX2 distribution. All moments are measured requiring minimum lepton momenta between 0.8 GeV/c and 1.9 GeV/c in the rest frame of the B meson. Performing a simultaneous fit to the measured moments nXk up to order k = 6 combined with other measurements of moments of the lepton-energy spectrum in decays B 2!Xcl[nu] and moments of the photon-energy spectrum in decays B 2!Xs[gamma], we determine the quark-mixing parameter.
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Languages : en
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A preliminary determination of the first moment of the hadronic mass distributionM[sub X][sup 2] -[bar m][sub D][sup 2] in semileptonic B decays has been obtained as a function of the minimum lepton momentum, ranging from 0.9 to 1.6 GeV/c. The measurement is based on a new technique involving B[bar B] events in which one fully reconstructed B meson decays hadronically and the recoiling B decays semileptonically. The mass of the hadrons in the semileptonic decay is determined from a kinematic fit to the whole event. For different minimum lepton momenta, the mass distribution is decomposed into contributions from various charm resonant states and a non-resonant contribution, allowing for the determination of the first moment. From these moments the Heavy Quark Effective Theory (HQET) parameters[lambda][sub 1] and[bar[Lambda]] can be derived. For lepton momenta in the B rest frame above 1.5 GeV/c, we find a first moment that is compatible with existing measurements. However, if we extend the measurement to lower values of lepton momenta, the data can only be described by Operator Product Expansion calculations if we use significantly different values for[bar[Lambda]] and[lambda][sub 1] than obtained from earlier measurements based on lepton momentum spectra and the photon spectrum in b[yields] s[gamma] transitions.
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Category :
Languages : en
Pages : 268
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Languages : en
Pages :
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A measurement of the first four moments of the hadronic mass distribution in B [yields] C[sub c][ell][bar [nu]] decays is presented for minimum lepton momenta varying between 0.9 and 1.6 GeV, using data recorded with the BABAR detector. Furthermore, a measurement of the inclusive electron energy spectrum for semileptonic B decays together with a measurement of its first, second and third moments for minimum electron energies between 0.6 and 1.5 GeV is reported. We determine the inclusive B [yields] X[sub c][ell][bar [nu]] branching fraction, [Beta][sub c[ell][nu]], the CKM matrix element V[sub cb], and other heavy-quark parameters from a simultaneous fit to the measured moments.
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Languages : en
Pages : 4
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A preliminary measurement of the first moments of the hadron mass M(subscript x) in B --> X lv decays by the BABAR Collaborations is reported. This measurement is performed as a function of the minimum lepton momentum.
Author: Verena Klose
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Languages : en
Pages : 0
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