We consider τ -lepton mass effects in the cascade decays H → Z(→ ℓ + ℓ − ) + Z * (→ τ + τ − ) and H → W − (→ ℓ −ν ℓ ) + W + * (→ τ + ν τ ). Since the scale of the problem is set by the off-shellness q 2 of the respective gauge bosons in the limits ( for the angular decay distributions of the final-state leptons. We also briefly consider the corresponding off-shell -off-shell decays H

We provide analytical results for the O(α s ) corrections to the double-spin density matrix elements in the reaction e + e − → tt. These concern the elements ll, lt, ln, tt, tn, and nn of the double-spin density matrix elements where l, t, n stand for longitudinal, transverse and normal orientations with respect to the beam frame spanned by the electron and the top quark momentum.

We consider identical particle and lepton mass effects in the cascade decay H →Since the scale of the problem is set by the offshellness p 2 a and p 2 b of the respective gauge bosons in the limits (4m) and not by m 2 H , lepton mass effects are nonnegligible in particular close to the threshold of the off-shell decays. We calculate the rates and single angle decay distributions and compare them with the corresponding rates and single angle decay distributions for the nonidentical particle decays H → Z * (→ e + e − ) + Z * (→ µ + µ − ) involving negligible lepton masses.

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