O(αs) spin-spin correlations for top and bottom quark production in e+e− annihilation

We present the full O(αs) longitudinal spin-spin correlations for heavy-quark pair production at e+e− high-energy colliders in closed analytical form. In such reactions, quark and antiquark have strongly correlated spins, and the longitudinal components are dominant. For the explicit computation of the QCD bremsstrahlung contributions, new phase-space integrals are derived. Explicit numerical estimates are given for tt̄ and bb̄ production. Around the Z-peak, QCD one-loop corrections depolarize the spin-spin asymmetry for bottom quark pairs by approximately −4%. For top pair production, we find at 350 GeV a 0.6% increased polarization over a value of 0.4 in the longitudinal correlation. For more than 1 TeV the O(αs) corrections enhance depolarization to −2% in the top-pair case.