Observation of charmless hadronic B decays

Abstract Four candidates for charmless hadronic B decay are observed in a data sample of four million hadronic Z decays recorded by the aleph detector at lep . The probability that these events come from background sources is estimated to be less than 10 −6 . The average branching ratio of weakly decaying B hadrons (a mixture of B d 0 , B s 0 and Λ b weighted by their production cross sections and lifetimes, here denoted B) into two long-lived charged hadrons (pions, kaons or protons) is measured to be Br (B → h + h − ) = (1.7 −0.7 +1.0 ± 0.2) × 10 −5 . The relative branching fraction Br( B d(s) 0 → π + π − (K − )) Br( B d(s) 0 → h + h − ) is measured to be 1.0 −0.3 −0.1 +0.0 +0.0 . In addition, branching ratio upper limits are obtained for a variety of exclusive charmless hadronic two-body decays of B hadrons.