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arXiv 1606.07063hep-phhep-exnucl-exnucl-th
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在SCET中使用半包含射流函数的射流子结构

Jet substructure using semi-inclusive jet functions within SCET

Zhong-Bo Kang, Felix Ringer, Ivan Vitev

备注：
28 pages, 6 figures, published version
发表信息：
JHEP 11 (2016) 155
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摘要：

我们提出了一种新的方法来评估射流子结构可观的包容性射流测量，基于软共线有效理论（SCET）的框架内的半包容性射流功能。作为第一个例子，我们考虑喷流碎裂函数，其中一个强子$h$被确定在一个完全重建的喷流。我们引入了一个新的半包容碎裂喷流函数${\mathcal G}^h_i(z= ω_J/ω,z_h=ω_h/ω_J,ω_J, R,μ)$，它依赖于喷流半径$R$和引发喷流的部分子“$i$”的大光锥动量（$ω$）、喷流（$ω_J$）和强子$h$（$ω_h$）。射流破碎函数可以表示为半包容性的可观察的，在实际的实验测量的精神，而不是作为一个排他性的。我们证明了有效场论处理和标准微扰QCD计算的一致性，这种可观察到的次领先阶（NLO）。半包容的碎裂喷流函数${\mathcal G}_i^h(z,z_h, ω_J, R,μ)$的重整化群方程也被导出，并显示出完全遵循通常的类时碎裂函数的DGSTAL演化方程。新获得的RG方程可以用来执行的射流半径参数$R$的下一个到领先的对数（NLL $_R$）精度的单次多项式的重新计算。结合固定的NLO计算，我们得到了喷注内部强子分布的NLO+NLL $_R$结果。我们目前的数值计算结果$pp\to(\mathrm{jet}\,h)X$在新的框架，并发现与现有的大型强子对撞机的实验数据非常吻合。

英文摘要：

We propose a new method to evaluate jet substructure observables in inclusive jet measurements, based upon semi-inclusive jet functions in the framework of Soft Collinear Effective Theory (SCET). As a first example, we consider the jet fragmentation function, where a hadron $h$ is identified inside a fully reconstructed jet. We introduce a new semi-inclusive fragmenting jet function ${\mathcal G}^h_i(z= ω_J/ω,z_h=ω_h/ω_J,ω_J, R,μ)$, which depends on the jet radius $R$ and the large light-cone momenta of the parton `$i$' initiating the jet ($ω$), the jet ($ω_J$), and the hadron $h$ ($ω_h$). The jet fragmentation function can then be expressed as a semi-inclusive observable, in the spirit of actual experimental measurements, rather than as an exclusive one. We demonstrate the consistency of the effective field theory treatment and standard perturbative QCD calculations of this observable at next-to-leading order (NLO). The renormalization group (RG) equation for the semi-inclusive fragmenting jet function ${\mathcal G}_i^h(z,z_h, ω_J, R,μ)$ are also derived and shown to follow exactly the usual timelike DGLAP evolution equations for fragmentation functions. The newly obtained RG equations can be used to perform the resummation of single logarithms of the jet radius parameter $R$ up to next-to-leading logarithmic (NLL$_R$) accuracy. In combination with the fixed NLO calculation, we obtain NLO+NLL$_R$ results for the hadron distribution inside the jet. We present numerical results for $pp\to(\mathrm{jet}\,h)X$ in the new framework, and find excellent agreement with existing LHC experimental data.

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