Resonant structure and flavour tagging in the B pi(+/-) system using fully reconstructed B decays

Starting from a sample of four million hadronic Z decays collected with the ALEPH detector at LEP, 404 charged and neutral B mesons are fully reconstructed and used to look for resonant structure in the B pi. system. An excess of events is observed above the expected background in the B rr mass spectrum at a mass approximate to 5.7 GeV/c(2), consistent with the production and decay to B(*)pi of the B** states predicted by Heavy Quark Symmetry (HQS). In the framework of HQS, it is found that the mass of the B-2* State is (5739(-11)(+8)(stat)(-4)(+6)(syst))MeV/c(2) 2 and the relative production rate of the B * * system is BR(b --> B** --> B(*)pi)/BR(b --> Bu,d)= (31 +/- 9(stat)(-5)(+6)(syst))%. In the same sample of B mesons, significant B pi(+/-) charge-flavour correlations are observed, which may prove important for tagging the initial B state in future CP violation studies. (C) 1998 Published by Elsevier Science B.V. All rights reserved.