Buskulic, D (reprint author), INST NATL PHYS NUCL & PHYS PARTICULES, CNRS, PHYS PARTICULES LAB, F-74019 ANNECY LE VIEUX, FRANCE.
The Lambda(b) polarization in hadronic Z decays is measured in semileptonic decays from the average energies of the charged lepton and the neutrino. In a data sample of approximately 3 million hadronic Z decays collected by the ALEPH detector at LEP between 1991 and 1994, 462 +/- 31 Lambda(b) candidates are selected using (Lambda pi(+))-lepton correlations. From this event sample, the Lambda(b) polarization is measured to be P-Lambda b = -0.23(-0.20)(+0.24)(stat.)(-0.07)(+0.08)(syst.).