Performance, reliability and scalability in data access are key issues in the context of Grid computing and High Energy Physics (HEP) data analysis. We present the technical details and the results ...of a large scale validation and performance measurement achieved at the CNAF Tier1, the central computing facility of the Italian National Institute for Nuclear Research (INFN). The aim of this work is the evaluation of data access activity during analysis tasks within BaBar and ALICE computing models against two of the most used data handling systems in HEP scenario: GPFS and Scalla/Xrootd.
Using 980 fb−1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e+e− collider, we report a study of the electromagnetic decays of excited charmed baryons Ξc(2790) and ...Ξc(2815). A clear signal (8.6 standard deviations) is observed for ... and we measure: ... We also present evidence (3.8 standard deviations) for the similar decay of the Ξc(2790)0 and measure: ... The first quoted uncertainties are statistical and the second systematic. We find no hint of the analogous decays of the Ξc(2815)+ and Ξc(2790)+ baryons and set upper limits at the 90% confidence level of: ..., and ... Approximate values of the partial widths of the decays are extracted, which can be used to discriminate between models of the underlying quark structure of these excited states. (ProQuest: ... denotes formula omitted.)
We report the result for a search for the leptonic decay of B+→μ+νμ using the full Belle dataset of 711 fb−1 of integrated luminosity at the ϒ(4S) resonance. In the Standard Model leptonic B-meson ...decays are helicity and Cabibbo-Kobayashi-Maskawa suppressed. To maximize sensitivity an inclusive tagging approach is used to reconstruct the second B meson produced in the collision. The directional information from this second B meson is used to boost the observed μ into the signal B-meson rest frame, in which the μ has a monochromatic momentum spectrum. Though its momentum is smeared by the experimental resolution, this technique improves the analysis sensitivity considerably. Analyzing the μ momentum spectrum in this frame we find B(B+→μ+νμ)=(5.3±2.0±0.9)×10−7 with a one-sided significance of 2.8 standard deviations over the background-only hypothesis. This translates to a frequentist upper limit of B(B+→μ+νμ)<8.6×10−7 at 90% confidence level. The experimental spectrum is then used to search for a massive sterile neutrino, B+→μ+N, but no evidence is observed for a sterile neutrino with a mass in a range of 0–1.5 GeV. The determined B+→μ+νμ branching fraction limit is further used to constrain the mass and coupling space of the type II and type III two-Higgs-doublet models.
Using the data sample of 980 fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and ...Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}→Λπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.3±0.6(stat)±0.9(syst) MeV/c^{2} 1438.5±0.9(stat)±2.5(syst) MeV/c^{2}, an intrinsic width of 11.5±2.8(stat)±5.3(syst) MeV/c^{2} 33.0±7.5(stat)±23.6(syst) MeV/c^{2} with a significance of 7.5σ (6.2σ). As these two signals are very close to the Kover ¯N threshold, we also investigate the possibility of a Kover ¯N cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.
We report a study of Λc+→Λh+ and Λc+→Σ0h+ (h=K,π) decays based on a data sample of 980fb-1 collected with the Belle detector at the KEKB energy-asymmetric e+e- collider. The first results of direct ...CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, ACPdir(Λc+→ΛK+)=+0.021±0.026±0.001 and ACPdir(Λc+→Σ0K+)=+0.025±0.054±0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (ACPα). We measure ACPα(Λc+→ΛK+)=-0.023±0.086±0.071 and ACPα(Λc+→Σ0K+)=+0.08±0.35±0.14, which are the first ACPα results for SCS decays of charmed baryons. We search for Λ-hyperon CP violation in Λc+→(Λ,Σ0)π+ and find ACPα(Λ→pπ-)=+0.013±0.007±0.011. This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λc+ decays, B(Λc+→ΛK+)=(6.57±0.17±0.11±0.35)×10-4 and B(Λc+→Σ0K+)=(3.58±0.19±0.06±0.19)×10-4. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of Λc+→(Λ,Σ0)π+.
The first measurements of differential branching fractions of inclusive semileptonic B→X_{u}ℓ^{+}ν_{ℓ} decays are performed using the full Belle data set of 711 fb^{-1} of integrated luminosity at ...the ϒ(4S) resonance and for ℓ=e, μ. With the availability of these measurements, new avenues for future shape-function model-independent determinations of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| can be pursued to gain new insights in the existing tension with respect to exclusive determinations. The differential branching fractions are reported as a function of the lepton energy, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic B→X_{c}ℓ^{+}ν_{ℓ} decays and other processes, and corrected for resolution and acceptance effects.
We report the first observation of the decay Λ+c→pK+π- using a 980 fb-1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e- collider. This is the first observation of a ...doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ+c→pK+π-)/B(Λ+c→pK-π+)=(2.35±0.27±0.21)×10-3, where the uncertainties are statistical and systematic, respectively.
Using 980.6 fb−1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e+e− collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed ...decay ... . A clear ... signal is observed for ... with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions .../...=(1.32±0.12(stat)±0.10(syst))×10−2, from which we infer the branching fraction ... . The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode ... . (ProQuest: … denotes formulae omitted.)
We report a study of the charmless hadronic decay of the charged B meson to the three-body final state K+K−π+. The results are based on a data sample that contains 772×106 BB¯ pairs collected at the ...ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The measured inclusive branching fraction and direct CP asymmetry are (5.38±0.40±0.35)×10−6 and −0.170±0.073±0.017, respectively, where the first uncertainties are statistical and the second are systematic. The K+K− invariant mass distribution of the signal candidates shows an excess in the region below 1.5 GeV/c2, which is consistent with the previous studies from BABAR and LHCb. In addition, strong evidence of a large direct CP asymmetry is found in the low K+K− invariant-mass region.
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