论文标题
QCD重新召集的共线功能
Collinear functions for QCD resummations
论文作者
论文摘要
QCD平方幅度在共线极限中的奇异行为是通过与过程无关的结构拆分内核来分解和控制的。我们使用这些内核来定义可在QCD重新召集公式中使用的共线函数。通过在不同的相空间区域中整合分裂内核来获得不同的共线函数，该区域取决于刻板的观测值。共线功能取决于辅助矢量$ n^μ$，该$ n^μ$可以是轻度$（n^2 = 0）$或类似时间的$（n^2> 0）$。在横向摩托依赖性（TMD）共线函数的情况下，我们表明使用类似时间的辅助向量会避免速度差异，而如果$ n^2 = 0 $，则会存在。共线函数的扰动计算导致红外（IR）差异，这些差异可以针对IR有限函数正确分解，这些功能体现了对数增强的共线贡献对硬质散布横截面的贡献。我们评估了各种共线函数及其$ n^μ$依赖性在$ {\ cal o}（α_ {\ rm s}）$。 We compute the azimuthal-correlation component of the TMD collinear functions at ${\cal O}(α_{\rm S}^2)$, and we present the results of the ${\cal O}(α_{\rm S}^2)$ contribution of linearly-polarized gluons to transverse-momentum resummation formulae.超过$ {\ cal o}（α_ {\ rm s}^2）$，由于违反了严格的QCD平方弹药振幅的严格界线分解，因此初始状态碰撞部分的共线函数是过程取决于过程的。
The singular behaviour of QCD squared amplitudes in the collinear limit is factorized and controlled by splitting kernels with a process-independent structure. We use these kernels to define collinear functions that can be used in QCD resummation formulae of hard-scattering observables. Different collinear functions are obtained by integrating the splitting kernels over different phase-space regions that depend on the hard-scattering observables of interest. The collinear functions depend on an auxiliary vector $n^μ$ that can be either light-like $(n^2=0)$ or time-like $(n^2 > 0)$. In the case of transverse-momentum dependent (TMD) collinear functions, we show that the use of a time-like auxiliary vector avoids the rapidity divergences, which are instead present if $n^2=0$. The perturbative computation of the collinear functions lead to infrared (IR) divergences that can be properly factorized with respect to IR finite functions that embody the logarithmically-enhanced collinear contributions to hard-scattering cross sections. We evaluate various collinear functions and their $n^μ$ dependence at ${\cal O}(α_{\rm S})$. We compute the azimuthal-correlation component of the TMD collinear functions at ${\cal O}(α_{\rm S}^2)$, and we present the results of the ${\cal O}(α_{\rm S}^2)$ contribution of linearly-polarized gluons to transverse-momentum resummation formulae. Beyond ${\cal O}(α_{\rm S}^2)$ the collinear functions of initial-state colliding partons are process dependent, as a consequence of the violation of strict collinear factorization of QCD squared amplitudes.
