QCD Corrections to Inclusive Distributions of Leptons in Decays of Polarised Heavy Quarks*

Compact analytic expressions have been obtained for the first order perturbative QCD corrections to the inclusive spectra of the leptons in the semileptonic decays of polarised heavy quarks. Charmed and beautiful Λ baryons from Z decays can be viewed as sources of highly polarised charm and bottom quarks. Charged leptons and neutrinos from Λb and Λc decays can be used in the polarisation studies for the corresponding heavy quarks. Thus our results are applicable for the b quark polarisation measurements at LEP. Short lifetime enables polarisation studies for the top quark. The angular-energy spectra of the charged leptons are particularly useful in this respect whereas the distributions of the neutrinos are sensitive to deviations from the V-A structure of the charged weak current in the decay.