2,132 research outputs found
The BaBar Experiment’s Distributed Computing Model
No full textDominique Boutigny LAPP-CNRS/IN2P3 on behalf of the BaBar Collaboration’s Computing Group In order to face the expected increase in statistics between now and 2005, the BaBar experiment at SLAC is evolving its computing model toward a distributed multi-tier system. It is foreseen that data will be spread among Tier-A centers and deleted from the SLAC center. A uniform computing environment is being deployed in the centers, the network bandwidth is continuously increased and data distribution tools has been designed in order to reach a transfer rate of ~100 TB of data per year. In parallel, smaller Tier-B and C sites receive subsets of data, presently in Kanga-ROOT[1] format and later in Objectivity[2] format. GRID tools will be used for remote job submission.
CP violation studies in in BaBar and Belle
No full textWe present a preliminary measurement of the time-dependent CP asymmetries in decays of B
0 mesons to the final states D
(*)
π using data collected by the BaBar experiment at the PEP-II storage rings. B mesons decaying to D
π are fully reconstructed, while events containing B → D
(*)
π are selected using a full or a partial reconstruction technique. These results can be interpreted in terms of a constraint on the angles of the unitarity triangle to set a lower bound on . The Belle experiment at the KEK-B collider is performing the same kind of studies and a preliminary estimation of the achievable error is presented
Tarsis et Zélie / [par R. Le Vayer de Boutigny] ; Nouvelle édition... [par L.-D. Colson]
No full textObservation of the semileptonic decays B ---> D* tau- anti-nu(tau) and evidence for B ---> D tau- anti-nu(tau
No full textWe present measurements of the semileptonic decays B- --> D0 tau- nubar, B- --> D*0 tau- nubar, B0bar --> D+ tau- nubar, and B0bar --> D*+ tau- nubar, which are potentially sensitive to non--Standard Model amplitudes. The data sample comprises 232x10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector. From a combined fit to B- and B0bar channels, we obtain the branching fractions B(B --> D tau- nubar) = (0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and B(B --> D* tau- nubar) = (1.62 +/- 0.31 +/- 0.10 +/- 0.05)% (normalized for the B0bar), where the uncertainties are statistical, systematic, and normalization-mode-related
Prompt photon production in hadronic events at Lep
No full textWe review some recent results on photon emission off quarks obtained by the four LEP experiments. These experimental results are compared to different Monte-Carlo predictions and to an exact matrix element calculation at the order (ems). The estimation of the background coming from neutral hadron decays is also discussed
Measurement of B-0 -> D-s(*)D+*(-) branching fractions and B-0 -> D-s*D+*(-) polarization with a partial reconstruction technique
No full textWe present a study of the decays B-0 --> D-s((*)) D*-, using 20.8 fb(-1) of e(+)e(-) annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D-s((*)+) and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B-0 --> Ds+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and B(B-0 --> D-s(*+) D*-) = (1.97 +/- 0.15 +/- 0.30+/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D-s(+) --> phipi(+) branching fraction uncertainty. From the B-0 --> D-s(*+) D*- angular distributions, we measure the fraction of longitudinal polarization Gamma(L)/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization
Measurement of branching fractions of color-suppressed decays of the (B)over-bar(0) meson to D-(*)0 pi(0), D-(*)0 eta, D-(*)0 omega, and D-0 eta `
No full textUsing a sample of 88.8×10^6 BB̅ events collected with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center, we measure the branching fractions of seven color-suppressed B-meson decays: B(B0→D0π0)=[2.9±0.2(stat)±0.3(syst)]×10-4, B(B0→D*0π0)=[2.9±0.4(stat)±0.5(syst)]×10-4, B(B0→D0η)=[2.5±0.2(stat)±0.3(syst)]×10-4, B(B0→D*0η)=[2.6±0.4(stat)±0.4(syst)]×10-4, B(B0→D0ω)=[3.0±0.3(stat)±0.4(syst)]×10-4, B(B0→D*0ω)=[4.2±0.7(stat)±0.9(syst)]×10-4, and B(B0→D0η′)=[1.7±0.4(stat)±0.2(syst)]×10-4. We set the 90% confidence-level upper limit: B(B0→D*0η′)<2.6×10-4. The channels B0→D*0η, D*0ω, and D0η′ are seen with more than five-sigma statistical significance. All of these branching fractions are significantly larger than theoretical expectations based on the “naive” factorization model
Measurement of B0 --> Ds(*)+D*- branching fractions and B0 --> Ds*+D*- polarization with a partial reconstruction technique
No full textWe present a study of the decays B0→Ds (*)+D*-, using 20.8 fb-1 of e +e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstniction technique, in which only the Ds(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B0→Ds+D*-) = (1.03±0.14±0.13±0.26)% and B(B0→D* s+D*-) = (1.97±0.15±0. 30±0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the Ds+ → φπ+ branching fraction uncertainty. From the B 0→D*s+D*- angular distributions, we measure the fraction of longitudinal polarization ΓL/Γ = (51.9±5.0±2.8)%, which is consistent with theoretical predictions based on factorization
Exclusive initial-state-radiation production of the D(D)over-bar, D*(D)over-bar and D*(D)over-bar* systems
No full textWe perform a study of the exclusive production of in initial-state-radiation events, from e(+)e(-) annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium and possible new resonances. The data sample corresponds to an integrated luminosity of 384 fb(-1) and was recorded by the BABAR experiment at the PEP-II storage rings. The D (D) over bar, D*(D) over bar, D*(D) over bar* mass spectra show clear evidence of several psi resonances. However, there is no evidence for Y(4260) -> D*(D) over bar or Y(4260) -> D*(D) over bar*
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