Investigation of the decay of orbitally-excited B mesons and first measurement of the branching ratio \({\rm BR}({\rm B}^*_J \rightarrow{\rm B}^* \pi (X))\)

From about 4 million hadronic \(\rm Z^0\) decays recorded by the OPAL detector on and near to the \(\rm Z^0\) resonance, we select a sample of more than 570 000 inclusively reconstructed B mesons. Orbitally-excited mesons\({\rm B}^*_J\) are reconstructed using \({\rm B}\pi^\pm\) combinations. Independently, \({\rm B}^*\) mesonsare reconstructed using the decay ${\rm B}^*\rightarrow{\rm B}{\gamma}\(. The selected \){\rm B}^*$ candidates are used to obtain samples enriched or depleted in the decay \({\rm B}^*_J \rightarrow{\rm B}^* \pi^{\pm}(X)\), where (X) refers to decay modes with or without additional accompanying decay particles. From the number of signal candidates in the \({\rm B}\pi^\pm\) mass spectra of these two samples, we perform the first measurement of the branching ratio of orbitally-excited B mesonsdecaying into \({\rm B}^*\pi(X)\):