The decay B* --> B gamma has been observed with the DELPHI detector at LEP, where the B* meson is produced in Z boson decays, The combination of inclusively reconstructed B mesons with well-measured converted photons yields a measurement of the flavour-averaged B* - B mass difference of 45.5 +/- 0.3 (stat.) +/- 0.8 (syst.) MeV/c(2). 95% confidence level upper limits at 6 MeV/c(2) are placed on both the isospin (i.e, B+-B-0) and the B-s-B-ud splitting of the mass difference, The production ratio of B* to B mesons in Z decays is measured to be 0.72 +/- 0.03 (stat.) +/- 0.06 (syst.). Limits on the production cross-section of other hypothetical excited B hadron states decaying radiatively are established. The differential B* cross section has been measured to be in good agreement with the average b fragmentation, yielding an average fractional B* energy of [x(E)] = 0.695 +/- 0.009 (stat.) +/- 0.013 (syst.). From the decay angular distribution the relative contribution of longitudinal B* polarisation states is measured to be sigma(L)/(sigma(L) + sigma(T)) = 0.32 +/- 0.04 (stat.) +/- 0.03 (syst.).

B-asterisk Production In Z-decays

BIANCHI, Fabrizio;MIGLIORE, Ernesto;ROMERO, Alessandra;
1995-01-01

Abstract

The decay B* --> B gamma has been observed with the DELPHI detector at LEP, where the B* meson is produced in Z boson decays, The combination of inclusively reconstructed B mesons with well-measured converted photons yields a measurement of the flavour-averaged B* - B mass difference of 45.5 +/- 0.3 (stat.) +/- 0.8 (syst.) MeV/c(2). 95% confidence level upper limits at 6 MeV/c(2) are placed on both the isospin (i.e, B+-B-0) and the B-s-B-ud splitting of the mass difference, The production ratio of B* to B mesons in Z decays is measured to be 0.72 +/- 0.03 (stat.) +/- 0.06 (syst.). Limits on the production cross-section of other hypothetical excited B hadron states decaying radiatively are established. The differential B* cross section has been measured to be in good agreement with the average b fragmentation, yielding an average fractional B* energy of [x(E)] = 0.695 +/- 0.009 (stat.) +/- 0.013 (syst.). From the decay angular distribution the relative contribution of longitudinal B* polarisation states is measured to be sigma(L)/(sigma(L) + sigma(T)) = 0.32 +/- 0.04 (stat.) +/- 0.03 (syst.).
1995
68
353
362
P. ABREU;W. ADAM;T. ADYE;E. AGASI;I. AJINENKO;R. ALEKSAN;G. D. ALEKSEEV;P. P. ALLPORT;S. ALMEHED;S. J. ALVSVAAG;U. AMALDI;S. AMATO;A. AND...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/103774
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