A measurement of vertical bar V-cb vertical bar using (B)over-bar(0)->D(*+)l(-)(v)over-bar(l) decays

摘要

We report a measurement of the Cabibbo-Kobayashi-Maskawa matrix element V-cb. From approximately 4.2 million hadronic Z(O) decays recorded with the OPAL detector, a sample is selected containing 1251 +/- 125 (B) over bar(0) --> D*+ l(--)nu- xi candidates, where l is either an electron or a muon, Using Heavy Quark Effective Theory calculations for the decay form factor at zero recoil of the D*+ meson in the (B) over bar(0) rest frame, we derive V-cb = [36.0 +/- 2.1 (stat) +/- 2.4 (syst) +/- 1.2 (theory)] x 10(-3).