论文标题
NLO面向大规模夸克的事件形状分布
NLO Oriented Event-Shape Distributions for Massive Quarks
论文作者
论文摘要
在本文中，我们计算了该过程的横截面$ e^+e^ - \至q \ edline q+x $，带有$ q $ a the heek quark，在给定事件形状$ e $中的差异和推力轴和梁方向之间的角度$θ_t$。这些可观察的物品通常称为面向事件形状，并且已经表明，$θ_t$依赖性可以分为两个结构，称为无方向性和角度的项。由于已经知道了无方向的部分，因此我们计算固定顺序中的差分和累积分布，最高为$ \ Mathcal {o}（α_s）$。我们的结果表明，对于矢量电流，与轴向矢量电流或无质量夸克相比，有一个非零$ \ MATHCAL {O}（α_s^0）$贡献。这需要对向量当前的一个人期望以$ \ mathcal {o}（α_s）$以及在添加时应取消的真实和虚拟辐射图中的红外差异期望奇数。在现象学方面，考虑到电动因素增强了矢量电流，这意味着有限的底部质量效应是一种重要的校正，因为它们不会受到强耦合的力量的阻尼，因此在精确研究中不能忽略。最后，我们表明矢量电流的总角分布在阈值时具有SOMMERFELD的增强。
In this article we compute the cross section for the process $e^+e^- \to Q\overline Q+X$, with $Q$ a heavy quark, differential in a given event shape $e$ and the angle $θ_T$ between the thrust axis and the beam direction. These observables are usually referred to as oriented event shapes, and it has been shown that the $θ_T$ dependence can be split in two structures, dubbed the unoriented and angular terms. Since the unoriented part is already known, we compute the differential and cumulative distributions in fixed-order for the angular part up to $\mathcal{O}(α_s)$. Our results show that, for the vector current, there is a non-zero $\mathcal{O}(α_s^0)$ contribution, in contrast to the axial-vector current or for massless quarks. This entails that for the vector current one should expect singular terms at $\mathcal{O}(α_s)$ as well as infrared divergences in real- and virtual-radiation diagrams that should cancel when added up. On the phenomenological side, and taking into account that electroweak factors enhance the vector current, it implies that finite bottom-mass effects are an important correction since they are not damped by a power of the strong coupling and therefore cannot be neglected in precision studies. Finally, we show that the total angular distribution for the vector current has a Sommerfeld enhancement at threshold.
