ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2014, vol. 89, p. -
Evidence for semileptonic B-→ pp̄ℓ- ν̄ℓ decays
We find evidence for the semileptonic baryonic decay B-→pp̄ℓ- ν̄ℓ (ℓ=e, μ), based on a data sample of 772 million BB̄ pairs collected at the Ï (4S) resonance with the Belle detector at the KEKB asymmetric-energy electron-positron collider. A neural-network based hadronic B-meson tagging method is used in this study. The branching fraction of B-→pp̄ℓ-ν̄ℓ is measured to be (5.8-2.1+2.4(stat) ±0.9(syst))×10-6 with a significance of 3.2σ, where lepton universality is assumed. We also estimate the corresponding upper limit: B(B-→pp̄ℓ-ν̄ℓ)<9.6×10-6 at the 90% confidence level. This measurement helps constrain the baryonic transition form factor in B decays. © 2014 American Physical Society.