J/psi mesons have been reconstructed from their decay to mu(+)mu(-) and e(+)e(-), using the data collected by the DELPHI experiment during 1991 and 1992 at the LEP collider. From about 1 million hadronic Z decays 153 +/- 17 J/psi were found, 5.4 +/- 2.3 psi' were obtained in the channel J/psi(--> mu(+)mu(-))pi(+)pi(-) and 6.4 +/- 2.7 chi(c) in the channel J/psi(--> mu(+)mu(-))gamma. As the dominant source of J/psi mesons is from b quarks, the following branching ratios: Br(b-->J/psi X) = (1.12 +/- 0.12 (stat.) +/- 0.10 (syst.))%, Br(b --> psi' X) = (0.48 +/- 0.22 (stat.) +/- 0.10 (syst.))%, Br(b-->chi(cl) X) = (1.4 +/- 0.6 (stat.)(-0.2)(+0.4) (syst.))% were measured. From the proper time distribution of the J/psi sample, the average lifetime of b-hadrons decaying into J/psi was found to be: tau(B) = 1.50(-0.21)(+0.24) (stat.) +/- 0.03 (syst.) ps. A search for completely reconstructed B meson decays to final states including a J/psi gave a signal of 15 +/- 5 events.

J/Psi-production in the hadronic decays of the Z

CACCIA, MASSIMO;PREST, MICHELA;
1994

Abstract

J/psi mesons have been reconstructed from their decay to mu(+)mu(-) and e(+)e(-), using the data collected by the DELPHI experiment during 1991 and 1992 at the LEP collider. From about 1 million hadronic Z decays 153 +/- 17 J/psi were found, 5.4 +/- 2.3 psi' were obtained in the channel J/psi(--> mu(+)mu(-))pi(+)pi(-) and 6.4 +/- 2.7 chi(c) in the channel J/psi(--> mu(+)mu(-))gamma. As the dominant source of J/psi mesons is from b quarks, the following branching ratios: Br(b-->J/psi X) = (1.12 +/- 0.12 (stat.) +/- 0.10 (syst.))%, Br(b --> psi' X) = (0.48 +/- 0.22 (stat.) +/- 0.10 (syst.))%, Br(b-->chi(cl) X) = (1.4 +/- 0.6 (stat.)(-0.2)(+0.4) (syst.))% were measured. From the proper time distribution of the J/psi sample, the average lifetime of b-hadrons decaying into J/psi was found to be: tau(B) = 1.50(-0.21)(+0.24) (stat.) +/- 0.03 (syst.) ps. A search for completely reconstructed B meson decays to final states including a J/psi gave a signal of 15 +/- 5 events.
DELPHI; B meson; b tagging; Z0 decay
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11383/1791242
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