Data from Z decays in DELPHI have been searched for bar(B0d) --> D*+ l- bar(nu) with the D*+ decaying to D0 pi+ and D0 --> K- pi+, K- pi+ pi+ pi- or K- pi+ pi0. These events are used to measure the CKM matrix element |Vcb| and the form factor slope, rho(A1)^2: F_D*(1) |Vcb| = 0.0392 +/- 0.0018 +/- 0.0023; rho(A1)^2 = 1.32 +/- 0.15 +/- 0.33 corresponding to a branching fraction: BR(bar(B0d) --> D*+ l-bar(nu)) = (5.90 +/- 0.22 +/- 0.50)\%. Combining these and previous DELPHI measurements gives: F_D*(1)|Vcb| = 0.0377 +/- 0.0011 +/- 0.0019, rho(A1)^2 = 1.39 +/- 0.10 +/- 0.33 and BR(bar(B0d) --> D*+ l- bar(nu)) = (5.39 +/- 0.11 +/- 0.34)% Using F_D*(1) = 0.91 +/- 0.04, yields: |Vcb| = 0.0414 +/- 0.0012(stat.) +/- 0.0021(syst.) +/- 0.0018 (theory). The b-quark semileptonic branching fraction into a D*+ emitted from higher mass charmed excited states has also been measured to be: BR(b --> D*+ X l- bar(nu)) = (0.67 +/- 0.08 +/- 0.10)\%.
Measurement of |V(cb)| using the semileptonic decay anti-B0(d) -> D*+ l- anti-nu(l)
AMAPANE, Nicola Carlo;MIGLIORE, Ernesto;ROMERO, Alessandra;
2004-01-01
Abstract
Data from Z decays in DELPHI have been searched for bar(B0d) --> D*+ l- bar(nu) with the D*+ decaying to D0 pi+ and D0 --> K- pi+, K- pi+ pi+ pi- or K- pi+ pi0. These events are used to measure the CKM matrix element |Vcb| and the form factor slope, rho(A1)^2: F_D*(1) |Vcb| = 0.0392 +/- 0.0018 +/- 0.0023; rho(A1)^2 = 1.32 +/- 0.15 +/- 0.33 corresponding to a branching fraction: BR(bar(B0d) --> D*+ l-bar(nu)) = (5.90 +/- 0.22 +/- 0.50)\%. Combining these and previous DELPHI measurements gives: F_D*(1)|Vcb| = 0.0377 +/- 0.0011 +/- 0.0019, rho(A1)^2 = 1.39 +/- 0.10 +/- 0.33 and BR(bar(B0d) --> D*+ l- bar(nu)) = (5.39 +/- 0.11 +/- 0.34)% Using F_D*(1) = 0.91 +/- 0.04, yields: |Vcb| = 0.0414 +/- 0.0012(stat.) +/- 0.0021(syst.) +/- 0.0018 (theory). The b-quark semileptonic branching fraction into a D*+ emitted from higher mass charmed excited states has also been measured to be: BR(b --> D*+ X l- bar(nu)) = (0.67 +/- 0.08 +/- 0.10)\%.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.