Analysis of B {u2192} ?l? Decays With BaBar PDF Download

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Languages : en
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As part of the BaBar project at SLAC to study the properties of B mesons, we have carried out a study of the exclusive charmless semileptonic decay mode B → ?l?, which can be used to determine the magnitude of the Cabbibo- Kobayashi-Maskawa matrix element Vub. Using simulated event samples, this study focuses on determining criteria on variables for selection of B → ?l? signal and suppression of background from other types of BB events and continuum processes. In addition, we determine optimal cuts on variables to ensure a good neutrino reconstruction. With these selection cuts, we were able to achieve a signal-to-background ratio of 0.68 and a signal efficiency of the order of 1%. Applying these cuts to a sample of 83 million BB events recorded by BaBar in e+e– collisions at the (4S) resonance, we obtain a yield of 115 ± 19 B → ?l? decays.

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Languages : en
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As part of the BaBar project at SLAC to study the properties of B mesons, we have carried out a study of the exclusive charmless semileptonic decay mode B → [omega]l[nu], which can be used to determine the magnitude of the Cabbibo- Kobayashi-Maskawa matrix element Vub. Using simulated event samples, this study focuses on determining criteria on variables for selection of B → [omega]l[nu] signal and suppression of background from other types of BB events and continuum processes. In addition, we determine optimal cuts on variables to ensure a good neutrino reconstruction. With these selection cuts, we were able to achieve a signal-to-background ratio of 0.68 and a signal efficiency of the order of 1%. Applying these cuts to a sample of 83 million BB events recorded by BaBar in e+e- collisions at the (4S) resonance, we obtain a yield of 115 ± 19 B → [omega]l[nu] decays.

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Languages : en
Pages : 146

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The authors present the results of the search for the decays B0/± → ?0/±? (previously observed) and B0 → ?? (for which currently only an upper limit exists). Together with B → K*? decays, B → (?/?? allow us to measure the ratio of CKM-matrix elements.

Author: Yi-Wen Chu
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Languages : en
Pages : 21

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As part of the BaBar project at SLAC to study the properties of B mesons, we have carried out a study of the exclusive charmless semileptonic decay mode B {yields} wlv, which can be used to determine the Cabbibo-Kobayashi-Maskawa matrix element V{sub ub}. Using simulated event samples, this study focuses on determining criteria on variables for selection of B {yields} wlv signal and suppression of background from other types of B{bar B} events and continuum processes. In addition, we determine optimal cuts on variables to ensure a good neutrino reconstruction. With these selection cuts, we were able to achieve a signal-to-background ratio of 0.68 and a signal efficiency of the order of 1%. Applying these cuts to a sample of 83 million B{bar B} events recorded by BaBar in e{sup +}e{sup -} collisions at the {Upsilon}(4S) resonance, we obtain a yield of 115 {+-} 19 B {yields} wlv decays.

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Languages : en
Pages : 4

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The authors present results on searches for the rare B decays B° → ll− (l = e or?) and B+ → K+?{bar?} in?(4S) decays. The data used in these analyses were collected with the BABAR detector at the PEP-II e+e− storage ring during the years 2000 and 2001. The B° → l+l− search was performed using an integrated luminosity of 54.4 fb−1 accumulated at the?(4S) resonance (about 60 million B{bar B} pairs) while the B+ → K+?{bar?} search was performed with 50.7 fb−1 (about 56 million B{bar B} pairs). Both analyses use an additional 6.4 fb−1 of data accumulated about 40 MeV below resonance. They see no evidence for a signal in either the B → l+l− or B → K+{nu}{bar {nu}} decay modes and set the following upper limits at the 90% CL:?(B° → e+e−)

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Languages : en
Pages : 138

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We measure the branching fraction of the exclusive charmless semileptonic decay B→ ?l?l, where l is either an electron or a muon, with the charged B meson recoiling against a tag B meson decaying in the charmed semileptonic modes B → Dl?l or B → D*l?l. The measurement is based on a dataset of 426.1 fb-1 of e+e- collisions at a CM energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric B Factory located at the SLAC National Accelerator Laboratory. We also calculate the relevant B → ? hadronic form factors to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element.

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Languages : en
Pages : 167

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The rare decay B → ?ll- is the simplest manifestation of a b → dl+l- flavor-changing neutral current (FCNC) process. This type of process only proceeds through penguin loop or box diagrams and is sensitive to physics at the electroweak scale. It can be used to constrain parameters of the Standard Model and its extensions. B → ?l+l- events have not yet been observed; the branching fraction is expected to be an order of magnitude smaller than the measured branching fraction for the similar B → Kl+l- decay. Using 230 million B$ar{B}$ meson pairs collected with the BABAR detector, we have done a search for the rare decay B →?l+l- . The data was produced in e+e- collision at the Y(4S) resonance in the PEP-II collider between 1999 and 2004. Four exclusive B-meson decay modes have been reconstructed: B+ → ?+l+l- and B0 → ?0l+l- , where l+ l- is either an electron pair (e+e-) or a muon pair (?+?-). We find no evidence for a signal, and we obtain upper limits on the branching fractions ?. Assuming the isospin relation ?(B+ → ?+l+l- ) 2 x ?B+/?B0 ?(B0 → ?0l+l-), we obtain an upper limit at 90% confidence level on the lepton-flavor-averaged branching fraction of B → ?l+l- to be ?(B → ?e?) 9.2 x 10sup-8 /supat 90% C.L. We have also reconstructed two control modes Bsup+/sup→ ?sup+/supesup±/sup?sup±/sup and Bsup0/sup → ?sup0/supesup±/sup?sup±/sup and we also obtain an upper limit at 90% confidence level on the lepton-flavor-violating decay B → ?e? of ?(B → ?e?) 9.2 x 10

Author: Karsten Koeneke
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Languages : en
Pages : 3

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A review of the most recent BABAR results on electroweak penguin B decays is presented. The focus of this paper is on the measurement of observables in the decays B {yields} X{sub s}{gamma}, B {yields} K{sup (*)}l{sup +}l{sup -} B {yields} K{sub s}{sup 0}{pi}{sup 0}{gamma} (time-dependent analysis) and B {yields} ({rho}/{omega}){gamma}.

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Languages : en
Pages : 3

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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?(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} → X{sub c}l{bar {nu}} decays allows for the determination of the nonperturbative parameters {bar {Lambda}} and?1 of Heavy Quark Effective Theory (HQET) and.

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Languages : en
Pages : 169

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Results of an amplitude analysis of the B±→ K± K∓ K± Dalitz plot are presented. The analysis is made using an integrated luminosity of 210.6 fb-1, recorded by the BABAR detector at the PEP-II asymmetric B Factory. This dataset corresponds to 231.8 million B$ar{B}$ pairs.