A data sample of about 3.0 million hadronic Z decays collected by the ALEPH experiment at LEP in the years 1991 through 1994 is used to make an inclusive selection of B hadron events. In this event sample 4227 +/- 140 +/- 252 B* mesons in the decay B* --> B gamma and 1944 +/- 108 +/- 161 B-u,B-d** mesons decaying into a B meson and a charged pion are reconstructed. Here and in the following B-u,B-d** denotes the eight L = 1 (b (u) over bar and (b (d) over bar) states and their charge conjugate. For the well established B* meson the following quantities are obtained: Delta M = M(B)* - M(B) = (45.30 +/- 0.35 +/- 0.87) MeV/c(2) and N-B*/(N-B + N-B*) = (77.1 +/- 2.6 +/- 7.0)%. The angular distribution of the photons in the B* rest frame is used to measure the relative contribution of longitudinal B* polarization states to be sigma(L)/(sigma(L) + sigma(T)) = (33 +/- 6 +/- 5)%. In the M(B pi)- M(B) mass difference resonance structure is observed at (424 +/- 4 +/- 10) MeV/c(2), for which the shape and position is consistent with the expectation for B-u,B-d** states decaying into B(*)pi(+/-). The relative production rate is determined to be BR(Z --> b --> B-u,B-d**)/BR(Z --> b --> B-u,B-d) = [27.9 +/- 1.6(stat) +/- 5.9(syst) (+3.9)(-5.6)(model)]%. where the third error reflects the uncertainty due to different production and decay models for the broad B-u,B-d** States.
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|Titolo:||Production of excited beauty states in Z decays|
|Data di pubblicazione:||1996|
|Digital Object Identifier (DOI):||10.1007/s002880050039|
|Appare nelle tipologie:||1.1 Articolo in rivista|