Two-parton contribution to the heavy-quark forward–backward asymmetry in NNLO QCD Original Research Article

Forward–backward asymmetries, image, are important observables for the determination of the neutral-current couplings of heavy quarks in inclusive heavy quark production, image. In view of the measurement perspectives on image at a future linear collider, precise predictions of image are required for massive quarks. We compute the contribution of the image final state to image to order image in the QCD coupling. We provide general formulae, and we show that this contribution to image is infrared-finite. We evaluate these two-parton contributions for b and c quarks on and near the Z resonance, and for t quarks above threshold. Moreover, near the image threshold we obtain, by expanding in the heavy-quark velocity β, an expression for image to order image and NNLL in β. This quantity is equal, to this order in β, to the complete forward–backward asymmetry image.