Author/Authors :
DELPHI Collaboration، نويسنده , , P. Abreu، نويسنده , , W. Adam، نويسنده , , T. Adye، نويسنده , , P. Adzic، نويسنده , , I. Ajinenko، نويسنده , , Z. Albrecht، نويسنده , , T. Alderweireld، نويسنده , , G.D. Alekseev، نويسنده , , R. Alemany، نويسنده , , T. Allmendinger، نويسنده , , P.P. Allport، نويسنده , , S. Almehed، نويسنده , , U. Amaldi، نويسنده , , N. Amapane، نويسنده , , S. Amato، نويسنده , , E.G Anassontzis، نويسنده , , P. Andersson، نويسنده , , A. Andreazza، نويسنده , , S. Andringa، نويسنده , , et al.، نويسنده ,
Abstract :
A study of b semileptonic decays into D, Dπ± and D∗π± final states is presented. The D0, D+ and D∗+ mesons are exclusively reconstructed in Z decay data recorded from 1992 to 1995 in the DELPHI experiment at LEP. The overall branching fractions are measured to be:BR(b→D0ℓ−ν̄ℓX)=(7.04±0.34 (stat)±0.36 (syst.exp)±0.17 (BRD))% ,BR(b→D+ℓ−ν̄ℓX)=(2.72±0.19 (stat)±0.16 (syst.exp)±0.18 (BRD))% ,BR(b→D∗+ℓ−ν̄ℓX)=(2.75±0.17 (stat)±0.13 (syst.exp)±0.09 (BRD))% ,where the D0 and D+ results include also contributions from D∗0 and D∗+ decays. A fit to the distribution of the π± impact parameter to the primary interaction vertex provides a measurement of the b semileptonic branching fractions into the D0π±X, D+π±X and D∗+π±X final states. Assuming that single pion decay modes of B mesons dominate, the partial rates for B̄→Dπℓ−νℓ̄ and B̄→D∗πℓ−νℓ̄ have been obtained, corresponding to a total branching fraction:BR(B̄→Dπℓ−νℓ̄)+BR(B̄→D∗πℓ−νℓ̄)=(3.40±0.52 (stat)±0.32 (syst))% .This result agrees well with the observed difference between the total B semileptonic branching fraction and the sum of the B̄→Dℓ−νℓ̄ and D∗ℓ−νℓ̄ branching fractions.
