Next-to-leading order QCD corrections to top quark spin correlations at hadron colliders: the reactions $g g \to t {\bar t} (g)$ and $g q ({\bar q}) \to t {\bar t} q ({\bar q})$

Abstract

We have computed the cross section for $t\bar t$ production by gluon-gluon fusion at next-to-leading order (NLO) in the QCD coupling, keeping the full dependence on the $t\bar t$ spins. Furthermore we have determined to the same order the spin dependent cross sections for the processes $g + q ({\bar q})\to t {\bar t} + q ({\bar q})$. Together with our previous results for $q + {\bar q} \to t {\bar t} (g)$ these results allow for predictions, at NLO QCD, of the hadronic production of $t\bar t$ pairs in a general spin configuration. As an application we have determined the degree of correlation of the $t$ and $\bar t$ spins at NLO, using various spin quantisation axes.

Figures (8)

• Figure 1: Dimensionless scaling functions $f^{(0)}_{gg}(\eta)$ (dotted), $f^{(1)}_{gg}(\eta)$ (full), and ${\tilde{f}}^{(1)}_{gg}(\eta)$ (dashed) that determine parton cross section $\hat{\sigma}_{gg}$.
• Figure 2: Dimensionless scaling functions $f^{(1)}_{gq}(\eta)$ (full) and ${\tilde{f}}^{(1)}_{gq}(\eta)$ (dashed) that determine $\hat{\sigma}_{gq}$.
• Figure 3: Dimensionless scaling functions $g^{(0)}_{gg}(\eta)$ (dotted), $g^{(1)}_{gg}(\eta)$ (full), and ${\tilde{g}}^{(1)}_{gg}(\eta)$ (dashed) that determine the expectation value $\hat{\sigma}_{gg}\langle {\cal O}_1 \rangle_{gg}$.
• Figure 4: Same as Fig.1, but for $\hat{\sigma}_{gg}\langle {\cal O}_2 \rangle_{gg}$.
• Figure 5: Same as Fig.1, but for $\hat{\sigma}_{gg}\langle {\cal O}_3 \rangle_{gg}$.