Study of B to Pi Ell Nu and B to Rho Ell Nu Decays and Determination of
Study of B to Pi Ell Nu and B to Rho Ell Nu Decays and Determination of

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Published: 2005

Total Pages: 8

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We present an analysis of exclusive charmless semileptonic B-meson decays based on 83 million B{bar B} pairs recorded with the BABAR detector at the ?(4S) resonance. Using isospin symmetry, we measure branching fractions ?(B° → ?−l+?) = (1.38 ± 0.10 ± 0.16 ± 0.08) x 10−4 and ?(B° → ?−l+?) = (2.14 ± 0.21 ± 0.48 ± 0.28) x 10−4, where the errors are statistical, experimental systematic, and due to form-factor shape uncertainties. We compare the measured distribution in q2, the momentum-transfer squared, with theoretical predictions for the form factors from lattice QCD and light-cone sum rules, and extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element.

Study of B to Pi L Nu and B to Rho L Nu Decays and Determination of
Study of B to Pi L Nu and B to Rho L Nu Decays and Determination of

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Published: 2011

Total Pages: 47

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We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 million B{bar B} pairs recorded with the BABAR detector at the ? (4S) resonance. We select four event samples corresponding to the decay modes B° → ?−l+?, B+ → ?°l+?, B° → ?−l+?, and B+ → ?°l+?, and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B → ?l? samples, and similarly the two B → ?l? samples, and measure the branching fractions ?(B° → ?−l+?) = (1.41 ± 0.05 ± 0.07) x 10−4 and ?(B° → ?°l+?) = (1.75 ± 0.15 ± 0.27) x 10−4, where the errors are statistical and systematic. We compare the measured distribution in q2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the CKM matrix element.

Measurement of the Relative Branching Fractions for B^- to D/D^{*}/D^{**}(D^{(*)}\pi) \ell^- \bar{\nu}_{\ell} with a Large Sample of Tagged B Mesons
Measurement of the Relative Branching Fractions for B^- to D/D^{*}/D^{**}(D^{(*)}\pi) \ell^- \bar{\nu}_{\ell} with a Large Sample of Tagged B Mesons

Author: B. Aubert

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Published: 2006

Total Pages: 20

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We present a study of B semileptonic decays into charm final states based on 211.7 fb{sup -1} of data collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. Using a novel technique based on the simultaneous fit of a set of variables reconstructed on the recoil of a B tagged in an hadronic decay mode, we measure the relative branching fractions {Lambda}(B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}{sub {ell}}) = 0.611 {+-} 0.022 (stat.) {+-} 0.027 (syst.) and {Lambda}(B{sup -} {yields} D**{sup 0})(D{sup (*)}{pi}){ell}{sup -}{bar {nu}}{sub {ell}}/{Lambda}(B{sup -} {yields} DX{ell}{sup -}{bar {nu}}{sub {ell}}) = 0.173 {+-} 0.017 (stat.) {+-} 0.021 (syst.).

Determination of the Branching Fraction for B Rightarrow X[sub C] Ell Nu Decays and of [verticalV[sub Cb][vertical from Hadronic-Mass and Lepton-Energy Moments
Determination of the Branching Fraction for B Rightarrow X[sub C] Ell Nu Decays and of [verticalV[sub Cb][vertical from Hadronic-Mass and Lepton-Energy Moments

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Published: 2004

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We determine the inclusive B [yields] X[sub c][ell][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 moments of the hadronic-mass and lepton-energy distributions in semileptonic B-meson decays, measured as a function of the lower limit on the lepton energy, using data recorded with the BABAR detector. Using Heavy Quark Expansions (HQEs) to order 1/m[sub b][sup 3], we extract [Beta][sub ce[nu]] = (10.61 [+-] 0.16[sub exp] [+-] 0.06[sub HQE])% and V[sub cb] = (41.4 [+-] 0.4[sub exp] [+-] 0.4[sub HQE] [+-] 0.6[sub th]) x 10[sup -3]. The stated errors refer to the experimental, HQE, and additional theoretical uncertainties.

Reconstruction of B- --] D*° E- Nu Decays and Determination of |Vcb|
Reconstruction of B- --] D*° E- Nu Decays and Determination of |Vcb|

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Published: 2001

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In this analysis the decay B- --> D*° e- nu is measured. The underlying data sample consists of about 226 million B-meson pairs accumulated on the Y(4S) resonance by the BABAR detector at the asymmetric e+e- collider PEP II. The reconstruction of the decay uses the channels D*° --> D° pi°, D° --> K- pi+ and pi° --> gamma gamma. The neutrino is not reconstructed. Since the rest frame of the B meson is unknown, the boost w of the D*° meson in the B meson rest frame is estimated by w'. The w' spectrum of the data is described in terms of the partial decay width dGamma/dw given by theory and the detector simulation translating each spectrum dGamma/dw into an expectation of the measured w' spectrum. dGamma/dw depends on a form factor F(w) parameterizing the strong interaction in the decay process. To find the best descriptive dGamma/dw a fit to the data determines the following two parameters of dGamma/dw: (i) F(1)|Vcb|, the product between F at zero D*°-recoil and the Quark mixing parameter |Vcb|; (ii) rho^2, a parameter of the form factor F(w). The former parameter scales the height of dGamma/dw and rho^2 varies the shape of it. The determined values of F(1)|Vcb|, rho^2 and the branching fraction BF(B- --> D*° e- nu) are F(1)|Vcb| = (35.8 +- 0.5 +- 1.5) x 10e-03, rho^2 = (1.08 +- 0.05 +- 0.09) and BF(B- --> D*° e- nu) = (5.60 +- 0.08 +- 0.42)%, where the uncertainties are statistical and systematic, respectively. The value of BF(B- --> D*° e- nu) has been determined by an integration of dGamma/dw over the allowed w range using the fitted values of F(1)|Vcb| and rho^2.

Study of Inclusive And Exclusive B ---] X/U L Nu Decays And the Measurement of
Study of Inclusive And Exclusive B ---] X/U L Nu Decays And the Measurement of

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Published: 2005

Total Pages: 5

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We report studies of B → X{sub u}l[nu] decays, based on a sample of 88 million B{bar B} events recorded with the BABAR detector. From both tagged and untagged B{bar B} events we have isolated inclusive charmless decays in kinematic regions for which the dominant background from B → X{sub c}l[nu] is reduced by making requirements on different variables: the electron energy E{sub l}, the momentum transfer q2, and the hadronic mass m{sub X}. Using theoretical calculations we extrapolate to the total decay rate to determine the CKM matrix element.

Study of the B to Xclnu Decays and Determination of
Study of the B to Xclnu Decays and Determination of

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Published: 2004

Total Pages:

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We report studies of semileptonic decays, B → X{sub c}l[nu], based on a sample of 88 million B{bar B} events recorded with the BABAR detector. We have measured four moments of the electron energy and hadronic mass distributions and determined the inclusive branching fraction, the CKM matrix element.