2,326 research outputs found

    Mass production of event simulations for the BaBar experiment using the Grid

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    The BaBar experiment has been taking data since 1999, investigating the violation of charge and parity (CP) symmetry in the field of High Energy Physics. Event simulation is an intensive computing task, due to the complexity of the algorithm based on the Monte Carlo method implemented using the GEANT engine. The simulation input data are stored in ROOT format, they are classified into two categories: conditions data for describing the detector status when data are recorded, and background triggers data for including the noise signal necessary to obtain a realistic simulation. In order to satisfy these requirements, in the traditional BaBar computing model events are distributed over several sites involved in the collaboration where each site manager centrally manages a private farm dedicated to simulation production. The new grid approach applied to the BaBar production framework is discussed along with the schema adopted for data deployment via Xrootd/Scalla servers, including data management using grid middleware on distributed storage facilities spread over the INFN-GRID network. A comparison between the two models is provided, describing also the custom applications developed for performing the whole production task on the grid and showing the results achieved

    Energy scan of the e+ehb(nP)π+πe^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections and evidence for Υ(11020)\Upsilon(11020) decays into charged bottomonium-like states

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    Using data collected with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider, we measure the energy dependence of the e+ehb(nP)π+πe^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections from thresholds up to 11.0211.02\,GeV. We find clear Υ(10860)\Upsilon(10860) and Υ(11020)\Upsilon(11020) peaks with little or no continuum contribution. We study the resonant substructure of the Υ(11020)hb(nP)π+π\Upsilon(11020) \to h_b(nP)\pi^+\pi^- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610)Z_b(10610) and Zb(10650)Z_b(10650). The relative fraction of these states is loosely constrained by the current data: the hypothesis that only Zb(10610)Z_b(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650)Z_b(10650) is produced is not excluded at a significant level.Comment: 8 pages, 4 figures, submitted to Physical Review Letter

    Search for Λc+ϕpπ0\Lambda_c^+\to\phi p \pi^0 and branching fraction measurement of Λc+Kπ+pπ0\Lambda_c^+\to K^-\pi^+ p \pi^0

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    We have searched for the Cabibbo-suppressed decay Λc+ϕpπ0\Lambda_c^+\to\phi p\pi^0 in e+ee^+e^- collisions using a data sample corresponding to an integrated luminosity of 915 fb1\rm fb^{-1}. The data were collected by the Belle experiment at the KEKB e+ee^+e^- asymmetric-energy collider running at or near the Υ(4S)\Upsilon(4S) and Υ(5S)\Upsilon(5S) resonances. No significant signal is observed, and we set an upper limit on the branching fraction of B(Λc+ϕpπ0)<15.3×105\mathcal{B}(\Lambda_c^+\to \phi p\pi^0) <15.3\times10^{-5} at 90% confidence level. The contribution for nonresonant Λc+K+Kpπ0\Lambda_c^+\to K^+K^- p\pi^0 decays is found to be consistent with zero and the corresponding upper limit on its branching fraction is set to be B(Λc+K+Kpπ0)NR<6.3×105\mathcal{B}(\Lambda_c^+\to K^+K^-p\pi^0)_{\rm NR} <6.3\times10^{-5} at 90% confidence level. We also measure the branching fraction for the Cabibbo-favored decay Λc+Kπ+pπ0\Lambda_c^+\to K^-\pi^+p\pi^0; the result is B(Λc+Kπ+pπ0)=(4.42±0.05(stat.)±0.12(syst.)±0.16(BNorm))%\mathcal{B}(\Lambda_c^+\to K^-\pi^+p\pi^0)= (4.42\pm0.05\, (\rm stat.) \pm 0.12\, (\rm syst.) \pm 0.16\, (\mathcal{B}_{\rm Norm}))\%, which is the most precise measurement to date. Finally, we have searched for an intermediate hidden-strangeness pentaquark decay Ps+ϕpP^+_s\to\phi p. We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of B(Λc+Ps+π0)×B(Ps+ϕp)<8.3×105{\cal B}(\Lambda_c^+\to P^+_s \pi^0)\times {\cal B}(P^+_s\to\phi p) <8.3\times 10^{-5} at 90% confidence level.Comment: 8 pages, 5 figures, 1 table, minor text change in version

    Studies of charmed strange baryons in the ΛD\Lambda D final state at Belle

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    We report the discovery of Ξc(3055)0\Xi_{c}(3055)^{0}, observed by its decay into the final state ΛD0\Lambda D^{0}, and present the first observation and evidence of the decays of Ξc(3055)+\Xi_c(3055)^{+} and Ξc(3080)+\Xi_c(3080)^{+} into ΛD+\Lambda D^{+}. We also perform a combined analysis of the ΛD+\Lambda D^{+} with the Σc++K\Sigma_{c}^{++}K^{-} and Σc++K\Sigma_{c}^{\ast ++}K^{-} decay modes to measure the ratios of branching fractions, masses and widths with improved accuracy. We measure the ratios of branching fractions B(Ξc(3055)+ΛD+)/B(Ξc(3055)+Σc++K)=5.09±1.01±0.76{\cal B}(\Xi_{c}(3055)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3055)^{+} \to \Sigma_{c}^{++}K^{-})=5.09\pm1.01\pm0.76, B(Ξc(3080)+ΛD+)/B(Ξc(3080)+Σc++K)=1.29±0.30±0.15{\cal B}(\Xi_{c}(3080)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.29\pm0.30\pm0.15, and B(Ξc(3080)+Σc++K)/B(Ξc(3080)+Σc++K)=1.07±0.27±0.01{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{\ast ++}K^{-})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.07\pm0.27\pm0.01, where the uncertainties are statistical and systematic. The analysis is performed using a 980 fb1^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider.Comment: Submitted to PR

    Observation of D0ρ0γD^0\to \rho^0\gamma and search for CPCP violation in radiative charm decays

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    We report the first observation of the radiative charm decay D0ρ0γD^0 \to \rho^0 \gamma and the first search for CPCP violation in decays D0ρ0γD^0 \to \rho^0 \gamma, ϕγ\phi\gamma, and K0γ\overline{K}{}^{*0} \gamma, using a data sample of 943 fb1^{-1} collected with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider. The branching fraction is measured to be B(D0ρ0γ)=(1.77±0.30±0.07)×105\mathcal{B}(D^0 \to \rho^0 \gamma)=(1.77 \pm 0.30 \pm 0.07) \times 10^{-5}, where the first uncertainty is statistical and the second is systematic. The obtained CPCP asymmetries, ACP(D0ρ0γ)=+0.056±0.152±0.006\mathcal{A}_{CP}(D^0 \to \rho^0 \gamma)=+0.056 \pm 0.152 \pm 0.006, ACP(D0ϕγ)=0.094±0.066±0.001\mathcal{A}_{CP}(D^0 \to \phi \gamma)=-0.094 \pm 0.066 \pm 0.001, and ACP(D0K0γ)=0.003±0.020±0.000\mathcal{A}_{CP}(D^0 \to \overline{K}{}^{*0} \gamma)=-0.003 \pm 0.020 \pm 0.000, are consistent with no CPCP violation. We also present an improved measurement of the branching fractions B(D0ϕγ)=(2.76±0.19±0.10)×105\mathcal{B}(D^0 \to \phi \gamma)=(2.76 \pm 0.19 \pm 0.10) \times 10^{-5} and B(D0K0γ)=(4.66±0.21±0.21)×104\mathcal{B}(D^0 \to \overline{K}{}^{*0} \gamma)=(4.66 \pm 0.21 \pm 0.21) \times 10^{-4}

    Search for a dark vector gauge boson decaying to π+π\pi^+ \pi^- using ηπ+πγ\eta \rightarrow \pi^+\pi^- \gamma decays

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    We report a search for a dark vector gauge boson UU^\prime that couples to quarks in the decay chain D+D0π+,D0KS0η,ηUγD^{*+} \to D^0 \pi^+, D^0 \to K^0_S \eta, \eta \to U^\prime \gamma, Uπ+πU^\prime \to \pi^+ \pi^-. No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of 10310210^{-3} - 10^{-2} in the UU^\prime mass range of 290 to 520 MeV/c2c^2. This analysis is based on a data sample of 976 fb1^{-1} collected by the Belle experiment at the KEKB asymmetric-energy e+ee^+e^- collider.Comment: 6 pages, 4 figure

    Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV

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    We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.Comment: 8 pages, 2 figure
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