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arXiv 0902.1915hep-ph
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无粲强子B衰变中的NNLO顶点修正:实部

NNLO vertex corrections in charmless hadronic B decays: Real part

Guido Bell

摘要:

计算了无粲强子B衰变的双圈顶点修正的实部,完成了QCD分解中拓扑树振幅的NNLO计算。在技术方面,我们表明,硬散射内核是免费的软共线红外发散在2圈的水平,这是一个复杂的减法程序后,涉及倏逝四夸克运营商。所考虑的修正的数值影响被认为是温和的,而拓扑树振幅的因子分解尺度依赖性显着降低在NNLO。我们特别没有发现一个增强的现象学上重要的比率|C/T|从微扰计算中。

英文摘要:

We compute the real part of the 2-loop vertex corrections for charmless hadronic B decays, completing the NNLO calculation of the topological tree amplitudes in QCD factorization. Among the technical aspects we show that the hard-scattering kernels are free of soft and collinear infrared divergences at the 2-loop level, which follows after an intricate subtraction procedure involving evanescent four quark operators. The numerical impact of the considered corrections is found to be moderate, whereas the factorization scale dependence of the topological tree amplitudes is significantly reduced at NNLO. We in particular do not find an enhancement of the phenomenologically important ratio |C/T| from the perturbative calculation.

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