Determination of P(c -> D*(+)) and BR(c -> l(+)) at LEP 1

The probability P(c --> D*(+)) that a charm quark fragments into a D*+ meson and the c --> l(+) semileptonic branching fraction were measured in Z(0) decay into c (c) over bar events. From the analysis of 3.5 Million Z(0) events collected from 1992 to 1995, a sample of charm meson decays with 81% c (c) over bar purity was selected. The product of the c --> D*(+) fragmentation probability times the D*(+) --> D(0)pi(+) branching fraction was measured to be: P(c --> D*(+)).BR(D*(+) --> D(0)pi(+)) = 0.174 +/- 0.010(stat) +/- 0.004(syst). Using the world averaged value for BR(D*+ --> D(0)pi(+)), the fragmentation probability is inferred: P(c --> D*(+)) = 0.255 +/- 0.015(stat) +/- 0.006(syst) +/- 0.005(syst.BR). From the same sample, 1828 +/- 51 identified leptons in the opposite hemisphere were selected. From this sample, the charm semileptonic branching fraction was measured to be: BR(c --> l(+)) = 0.0958 +/- 0.0042(stat) +/- 0.0028(syst).