Two-parton contribution to the heavy-quark forward–backward asymmetry in NNLO QCD
- 作者：W. Bernreuther ; R. Bonciani ; T. Gehrmann ; R. Heinesch ; T. Leineweber ; P. Mastrolia and E. Remiddi
- 关键词：Electroweak measurements ; Forward– ; backward asymmetry ; Heavy quarks ; Precision calculations ; QCD corrections
- 刊名：Nuclear Physics B
- 出版年：2006
- 期刊代码：45_05503213
- 类别：ph
- 出版时间：21 August 2006
- 卷：750
- 期：1-2
- 页码：83-107
- 文件大小：337 K
摘要
Forward–backward asymmetries, , are important observables for the determination of the neutral-current couplings of heavy quarks in inclusive heavy quark production, e+e−→γ*,Z*→Q+X. In view of the measurement perspectives on at a future linear collider, precise predictions of are required for massive quarks. We compute the contribution of the final state to to order in the QCD coupling. We provide general formulae, and we show that this contribution to 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 threshold we obtain, by expanding in the heavy-quark velocity β, an expression for to order and NNLL in β. This quantity is equal, to this order in β, to the complete forward–backward asymmetry .