From approximately 3 million hadronic decays of Z bosons recorded with the ALEPH detector at LEP, a sample of 410 +/- 32 over bar B(0) -> D*(+)l(-)nu(l) candidates is selected, where l is either an electron or a muon. The differential decay rate dGamma(over bar B(0) -> D*(+)l(-)nu(l))/(domega) from this sample is fitted, yielding a value for the product of the CKM matrix element |Vcb| and the normalisation of the decay form factor at the point of zero recoil of the D*(+) meson F(omega = 1)|Vcb| = (31.4 +/- 2.3(stat) +/- 2.5(syst)) x 10(-3). A value for |Vcb| is extracted using theoretical calculations of the form factor normalisation, with the result |Vcb| = (34.5 +/- 2.5(stat) +/- 2.7(syst) +/- 1.5(theory)) x 10(-3) From the integrated spectrum, the measured branching fraction is Br(over bar B(0) -> D*(+)l(-)nu) = (5.18 +/- 0.30(stat) +/- 0.62(syst))%.
A Measurement of the |Vcb| from over bar B(0) -> D*+ lepton- (nu bar)_l.
G. BATIGNANI;CIOCCI, MARIA AGNESE;FERRANTE, ISIDORO;MESSINEO, ALBERTO MARIA;TONELLI, GUIDO EMILIO;G. TRIGGIANI;
1995-01-01
Abstract
From approximately 3 million hadronic decays of Z bosons recorded with the ALEPH detector at LEP, a sample of 410 +/- 32 over bar B(0) -> D*(+)l(-)nu(l) candidates is selected, where l is either an electron or a muon. The differential decay rate dGamma(over bar B(0) -> D*(+)l(-)nu(l))/(domega) from this sample is fitted, yielding a value for the product of the CKM matrix element |Vcb| and the normalisation of the decay form factor at the point of zero recoil of the D*(+) meson F(omega = 1)|Vcb| = (31.4 +/- 2.3(stat) +/- 2.5(syst)) x 10(-3). A value for |Vcb| is extracted using theoretical calculations of the form factor normalisation, with the result |Vcb| = (34.5 +/- 2.5(stat) +/- 2.7(syst) +/- 1.5(theory)) x 10(-3) From the integrated spectrum, the measured branching fraction is Br(over bar B(0) -> D*(+)l(-)nu) = (5.18 +/- 0.30(stat) +/- 0.62(syst))%.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.