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arXiv 1012.4230hep-phhep-ex
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次领先阶轻子衰变顶夸克对强子产生中的完全离壳效应

Complete off-shell effects in top quark pair hadroproduction with leptonic decay at next-to-leading order

Giuseppe Bevilacqua, Michal Czakon, Andreas van Hameren, Costas G. Papadopoulos, Malgorzata Worek

摘要:

首次给出了具有完全离壳效应的pp(p \bar{p})-> t \bar{t} -> W^+W^- b \bar{b} -> e^{+} v_{e} μ^{-} \bar v_μ b \bar{b} +X过程的次到首阶QCD修正结果.我们一致地考虑了{ \cal{O} }(α_{s}^3 α^4)阶的双共振、单共振和非共振顶夸克的贡献,这就要求对不稳定顶夸克引入一个复质量方案.此外,中间W玻色子被处理离壳。比较窄宽度近似的顶夸克,其中不可因式分解的修正不占。除了总的截面和它的尺度依赖性,几个微分分布在TeVatron运行II和LHC给出。在TeVatron的情况下,重新计算顶部的前后不对称性。在包含性选择切割的情况下,前后不对称性达到A^{t}_{FB} = 0.051 +/- 0.0013。此外,关于领先秩序的修正是积极的,TeVatron和47%的大型强子对撞机的顺序为2.3%。我们的NLO预测的尺度依赖性的研究表明,由于高阶修正的剩余理论不确定性是8%的TeVatron和9%的LHC。

英文摘要:

Results for next-to-leading order QCD corrections to the pp(p\bar{p}) -> t \bar{t} -> W^+W^- b\bar{b} -> e^{+} ν_{e} μ^{-} \barν_μ b \bar{b} +X processes with complete off-shell effects are presented for the first time. Double-, single- and non-resonant top contributions of the order {\cal{O}}(α_{s}^3 α^4) are consistently taken into account, which requires the introduction of a complex-mass scheme for unstable top quarks. Moreover, the intermediate W bosons are treated off-shell. Comparison to the narrow width approximation for top quarks, where non-factorizable corrections are not accounted for is performed. Besides the total cross section and its scale dependence, several differential distributions at the TeVatron run II and the LHC are given. In case of the TeVatron the forward-backward asymmetry of the top is recalculated afresh. With inclusive selection cuts, the forward-backward asymmetry amounts to A^{t}_{FB} = 0.051 +/- 0.0013. Furthermore, the corrections with respect to leading order are positive and of the order 2.3% for the TeVatron and 47% for the LHC. A study of the scale dependence of our NLO predictions indicates that the residual theoretical uncertainty due to higher order corrections is 8% for the TeVatron and 9% for the LHC.

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