CERN Accelerating science

Article
Report number CERN-PPE-95-108 ; FSU-SCRI-96-16
Title Production of excited beauty states in Z decays
Author(s) ALEPH Collaboration  Show all 417 authors
Publication 1996
Imprint 5 Sep 1995
Number of pages 24
Series (ALEPH Papers)
In: Z. Phys. C 69 (1996) 393-404
DOI 10.1007/BF02907419
Subject category Particle Physics - Experiment
Accelerator/Facility, Experiment CERN LEP ; ALEPH
Abstract 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 \pm 140 \pm 252 B^* mesons in the decay B^* \to B \gamma and 1944 \pm 108 \pm 161 B^{**} mesons decaying into a B meson and a charged pion are reconstructed. For the well established B^* meson the following quantities areobtained: \Delta M = M_{B^*} - M_{B} = (45.30\pm 0.35\pm 0.87) \mathrm{MeV}/c^2 and N_{B^*}/(N_B+N_{B^*}) = (77.1 \pm 2.6 \pm 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 \pm 6 \pm 5)\%.
Resonance structure in the M(B\pi)-M(B) mass difference is observed at (424 \pm 4 \pm 10) \mathrm{MeV}/c^2. Its shape and position is in agreement with the expectation for B^{**}_{u,d} states decaying into B_{u,d}^{(*)} \pi^\pm. The signal is therefore interpreted as arising from them. The relative production rate is determined to be \frac{BR(Z \to b \to B_{u,d}^{**})}{BR(Z \to b \to B_{u,d})} = [27.9 \pm 1.6(stat) \pm 5.9(syst) \phantom{a}^{+3.9}_{-5.6}(model)]\%. where the third error reflects the uncertainty due to different production and decay models for the broad B_{u,d}^{**} states.

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 Record created 1995-09-14, last modified 2018-09-24


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