O(αs) QCD corrections to spin correlations in the e−e+→tt

Using a generic spin basis, we present a general formalism of one-loop radiative corrections to the spin correlations in the top quark pair production at the Next Linear Collider, and calculate the O(αs) QCD corrections under the soft gluon approximation. We find that: (a) in off-diagonal basis, the O(αs) QCD corrections to eL−e+ (eR−e+) scattering process increase the differential cross sections of the dominant spin component t↑t̄↓ (t↓t̄↑) by ∼30% and ∼(0.1%−3%) depending on the scattering angle for s=400 GeV and 1 TeV, respectively; (b) in off-diagonal basis (helicity basis), the dominant spin component makes up 99.8% (∼53%) of the total cross section at both tree and one-loop level for s=400 GeV, and the off-diagonal basis therefore remains to be the optimal spin basis after the inclusion of O(αs) QCD corrections.