NLO QCD corrections to the production of $t t \bar Z$ in gluon fusion
Achilleas Lazopoulos, Kirill Melnikov, and Frank Petriello

We compute the ${\cal O}(\alpha_s)$ QCD corrections to the partonic process $gg \to t \bar{t} Z$ at the LHC. This partonic channel is the dominant component of the scattering process $pp \to t\bar{t}Z$, which will be important for measuring the $t \bar t Z$ electroweak couplings. We perform this calculation using a newly developed numerical technique for obtaining loop corrections. The ${\cal O}(\alpha_s)$ corrections increase the total cross section by up to $75\%$ for reasonable choices of the renormalization and factorization scales. Inclusion of these contributions decreases the residual scale dependence of the cross section coming from uncalculated higher order terms to $\pm 5\%$.

© 2008 The American Physical Society.