Search for the rare decays B → πℓ+ℓ- and B0 → ηℓ+ℓ-

Abstract

We present the results of a search for the rare flavor-changing neutral-current decays B → π ℓ + ℓ − ( π = π ± , π 0 and ℓ = e , μ ) and B 0 → η ℓ + ℓ − using a sample of e + e − → Υ ( 4 S ) → B ¯¯¯ B decays corresponding to 428 fb − 1 of integrated luminosity collected by the BABAR detector. No significant signal is observed, and we set an upper limit on the isospin and lepton-flavor averaged branching fraction of B ( B → π ℓ + ℓ − ) < 5.9 × 10 − 8 and a lepton-flavor averaged upper limit of B ( B 0 → η ℓ + ℓ − ) < 6.4 × 10 − 8 , both at the 90% confidence level. We also report 90% confidence level branching fraction upper limits for the individual modes B + → π + e + e − , B 0 → π 0 e + e − , B + → π + μ + μ − , B 0 → π 0 μ + μ − , B 0 → η e + e − , and B 0 → η μ + μ − .