论文标题

重新归一化组流量用于轨道功能矩

Renormalization Group Flows for Track Function Moments

论文作者

Jaarsma, Max, Li, Yibei, Moult, Ian, Waalewijn, Wouter, Zhu, Hua Xing

论文摘要

轨道函数描述了夸克和胶子碎片的集体效应,使其成为HADRON COLLIDERS射流子结构测量值的关键要素,基于轨道的测量可提供优质的角度分辨率。轨道功能的第一刻描述了沉积在带电颗粒中的平均能量,是一个简单且研究良好的对象。但是,对能流的较高点相关性的测量需要在结合过程中表征波动的表征,从理论上讲,通过轨道功能的较高力矩描述。在本文中,我们得出了轨道功能矩的重新归一化组(RG)演变方程的结构。我们表明,节能产生了一个移动对称性,该对称性允许以累积剂为$κ(n)$编写进化方程,以及Quark和Gluon Track函数的第一刻($δ$)之间的差异。然后,前三个累积物的独特性将其全阶进化固定为DGLAP,直到涉及$δ$的校正,这些校正在数值上由于现象学跟踪功能的扰动扩展而在数值上被抑制。但是,在第四个累积剂中,超越了$κ(4)$ $κ(2)^2 $等累积的RG混合。我们分析以$ \ Mathcal {o}(α_s^2)$在第六刻的分析计算进化方程,并研究相关的RG流量。这些结果允许使用轨道研究能量流中最多六点相关性,从而为LHC的精确喷射子结构铺平了道路。

Track functions describe the collective effect of the fragmentation of quarks and gluons into charged hadrons, making them a key ingredient for jet substructure measurements at hadron colliders, where track-based measurements offer superior angular resolution. The first moment of the track function, describing the average energy deposited in charged particles, is a simple and well-studied object. However, measurements of higher-point correlations of energy flow necessitate a characterization of fluctuations in the hadronization process, described theoretically by higher moments of the track function. In this paper we derive the structure of the renormalization group (RG) evolution equations for track function moments. We show that energy conservation gives rise to a shift symmetry that allows the evolution equations to be written in terms of cumulants, $κ(N)$, and the difference between the first moment of quark and gluon track functions, $Δ$. The uniqueness of the first three cumulants then fixes their all-order evolution to be DGLAP, up to corrections involving powers of $Δ$, that are numerically suppressed by an effective order in the perturbative expansion for phenomenological track functions. However, at the fourth cumulant and beyond there is non-trivial RG mixing into products of cumulants such as $κ(4)$ into $κ(2)^2$. We analytically compute the evolution equations up to the sixth moment at $\mathcal{O}(α_s^2)$, and study the associated RG flows. These results allow for the study of up to six-point correlations in energy flow using tracks, paving the way for precision jet substructure at the LHC.

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