O(\alpha_s) QCD Corrections to Spin Correlations in $e^{-}{e}^{+}\to t\bar{t}$ process at the NLC

Abstract

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(\alpha_s) QCD corrections under the soft gluon approximation. We find that: (a) in Off-diagonal basis, the $O({\alpha }_s)$ QCD corrections to $e_L^{-}{e}^{+}$ ($e_R^{-}{e}^{+}$) scattering process increase the differential cross sections of the dominant spin component $t_{\uparrow }{\bar{t}}_{\downarrow }$ ($t_{\downarrow }{\bar{t}}_{\uparrow }$) by $\sim 30$ and $\sim (0.1$ depending on the scattering angle for $\sqrt{s}=400GeV$ and 1 TeV, respectively; (b) in {Off-diagonal basis} (Helicity basis), the dominant spin component makes up 99.8% ($\sim 53$) of the total cross section at both tree and one-loop level for $\sqrt{s}=400GeV$, and the Off-diagonal basis therefore remains to be the optimal spin basis after the inclusion of $O({\alpha }_s)$ QCD corrections.

Comments: 12 pages, 4 figures, revised version (a few print mistakes are corrected, some numerical results are modified, and Fig.4 is added)