Observation of charmless B decays with the ALEPH detector at LEP

A search for hadronic charmless decays of B hadrons has been performed with the ALEPH detector at LEP. Four candidates have been observed in the h(+)h(-) channel. The probablity that these four candidates come from background was estimated to be less than 10(-6). The branching ratio of a B meson into two oppositely charged hadrons was measured to be Br(B --> h(+)h(-)) = (1.7(-0.7)(+1.0) +/- 0.2)x10(-5). The relative branching fraction Br(B-d(s)(o) --> pi(+)pi(-)(K-))/Br(B-d(s)(o) --> h+h(-)) was estimated to be (1.(+0.0)(-0.3) (+0.0)(-0.1)). A number of other decay channels of neutral or charged B mesons into charged pions have also been studied. Upper limits on the branching ratios have been computed.