Investigation of the Decay of Orbitally-ExcitedB Mesons and First Measurement of theBranching Ratio BR ( B J ! B ( X ) ) The OPAL

From about 4 million hadronic Z 0 decays recorded by the OPAL detector on and near to the Z 0 resonance, we select a sample of more than 570 000 inclusively reconstructed B mesons. Orbitally-excited mesons B J are reconstructed using B combinations. Independently , B mesons are reconstructed using the decay B ! B. The selected B candidates are used to obtain samples enriched or depleted in the decay B J ! B (X), where (X) refers to decay modes with or without additional accompanying decay particles. From the number of signal candidates in the B mass spectra of these two samples, we perform the rst measurement of the branching ratio of orbitally-excited B mesons decaying into B (X): where the rst error is statistical and the second systematic. If B J decay modes other than single pion transitions can be neglected the measured ratio corresponds to the branching ratio BR(B J ! B). In the framework of Heavy Quark Symmetry, a simultaneous t to the B mass spectra of the samples enriched or depleted in B J ! B (X) decays yields the mass and the width of the B 1 (3=2) state, as well as the branching ratio of B J mesons decaying into B : where the uncertainties are statistical and systematic, respectively.