par Abreu, Pedro;Bertrand, Daniel 
;Herquet, P. ; [et al.]
Référence Physics letters. Section B, 496, 1-2, page (43-58)
Publication Publié, 2000
;Herquet, P. ; [et al.]Référence Physics letters. Section B, 496, 1-2, page (43-58)
Publication Publié, 2000
Article révisé par les pairs
| Résumé : | The branching ratio for the leptonic decay of charged B mesons (B-→ τ-ν̄τ) has been measured using selected leptonic τ-→ ℓ-ντν̄ℓand hadronic τ-→ ντX decays in Z → bb̄ decays recorded by DELPHI at LEP1 in 1992-1995. The result, BR(B-→τ-ν̄τ) ≤ 1.1 × 10-3at the 90% confidence level, is consistent with standard model expectations and puts a 47 constraint on the ratio tan β/MH±<0.46 (GeV/c2)-1in the framework of models with two Higgs doublets (type II Higgs doublet model). From the missing energy distribution in Z → bb̄ decays without identified leptons, the b → τν̄τX branching ratio has been measured in the hadronic channel τ → ντX′. The result, BR (b → τν̄τX) = (2.19 ± 0.24 (stat) ± 0.39 (syst) %, is consistent with the Standard Model prediction and with previous experimental measurements. |
