15 research outputs found
Evidence for the decay
International audienceWe report a search for the charmless baryonic decay B0→pp¯π0 with a data sample corresponding to an integrated luminosity of 711 fb-1 containing (772±10)×106 BB¯ pairs. The data were collected by the Belle experiment running on the ϒ(4S) resonance at the KEKB e+e- collider. We measure a branching fraction B(B0→pp¯π0)=(5.0±1.8±0.6)×10-7, where the first uncertainty is statistical and the second is systematic. The signal has a significance of 3.1 standard deviations and constitutes the first evidence for this decay mode. We also search for the intermediate two-body decays B0→Δ+p¯ and B0→Δ¯-p, and set an upper limit on the branching fraction, B(B0→Δ+p¯)+B(B0→Δ¯-p)<1.6×10-6 at 90% confidence level
Measurements of branching fraction and asymmetry of the decay at Belle
International audienceWe report the measurement of the branching fraction and asymmetry for the decay. The analysis is performed on a data sample of 711 collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We obtain a branching fraction of and an of , where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are also observed in the differential branching fraction as functions of Dalitz variables
Measurement of and with a semileptonic tagging method
We report a measurement of the ratios of branching fractions and , where denotes an electron or a muon. The results are based on a data sample containing events recorded at the resonance with the Belle detector at the KEKB collider. The analysis utilizes a method where the tag-side meson is reconstructed in a semileptonic decay mode, and the signal-side is reconstructed in a purely leptonic decay. The measured values are and , where the first uncertainties are statistical and the second are systematic. These results are in agreement with the Standard Model predictions within and standard deviations, respectively, while their combination agrees with the Standard Model predictions within standard deviations
Test of lepton flavor universality in decays at Belle
We present a measurement of , the ratio of the branching fractions and , for both charged and neutral mesons. The ratio for charged mesons, , is the first measurement ever performed. The analysis is based on a data sample of , containing events, recorded at the resonance with the Belle detector at the KEKB asymmetric-energy collider
Test of lepton flavor universality and search for lepton flavor violation in decays
International audienceWe present measurements of the branching fractions for the decays B → Kμμ and B → Kee, and their ratio (R), using a data sample of 711 fb that contains 772 × 10 events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy ee collider. The ratio R is measured in five bins of dilepton invariant-mass-squared (q): q ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (> 14.18) GeV/c, along with the whole q region. The R value for q ∈ (1.0, 6.0) GeV/c is ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for R are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q ∈ (1.0, 6.0) GeV/c bin in the mode with muon final states. The measured differential branching fractions, /dq, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. We have also searched for lepton-flavor-violating B → Kμe decays and set 90% confidence-level upper limits on the branching fraction in the range of 10 for B → Kμe, and B → Kμe modes.[graphic not available: see fulltext