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arXiv 1609.06104hep-phhep-exnucl-th
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介质诱导射流演化中的多粒子关联和KNO标度

Multi-particle correlations and KNO scaling in the medium-induced jet evolution

Miguel A. Escobedo, Edmond Iancu

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31 pages, 7 figures
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摘要：

本文研究了高能喷流在弱耦合夸克-胶子等离子体中传播时，由介质诱导的连续分支所产生的胶子分布。我们表明，在适当的近似下，射流的演化可以描述为一个经典的随机过程，这是完全可解的。对于这个过程，我们构造了所有n点关联函数（能量空间中的n体密度）的精确解析解。一点函数和两点函数的相应结果是已知的，但对于更高点函数的结果是新的。这些结果表明，在分支过程中存在的共同祖先的强相关性。通过对这些n点函数在胶子能量上的积分，我们导出了平均胶子多重数$\langle N\rangle$以及用$p\ge 2$表示的高阶矩$\langle N^p\rangle$.我们发现，软胶子的多重性参数大，并显示出显着的规律性，称为Koba-Nielsen-Olesen（KNO）标度：约化的时刻$\langle N^p\rangle/\langle N\rangle^p$是纯数，独立于任何的物理参数的问题。我们认识到一个特殊的负二项分布，其特点是大的统计波动。这些预测可以在铅+铅碰撞在大型强子对撞机，通过事件的双喷流不对称性的测量事件。

英文摘要：

We study the gluon distribution produced via successive medium-induced branchings by an energetic jet propagating through a weakly-coupled quark-gluon plasma. We show that under suitable approximations the evolution of the jet can be described as a classical stochastic process, which is exactly solvable. For this process, we construct exact analytic solutions for all the n-point correlation functions (the n-body densities in the space of energy). The corresponding results for the one-point and the two-point functions were already known, but those for the higher-point functions are new. These results demonstrate strong correlations associated with the existence of common ancestors in the branching process. By integrating these n-point functions over the gluon energies, we deduce the mean gluon multiplicity $\langle N\rangle$ as well as the higher moments $\langle N^p\rangle$ with $p\ge 2$. We find that the multiplicities of the soft gluons are parametrically large and show a remarkable regularity, known as Koba-Nielsen-Olesen (KNO) scaling: the reduced moments $\langle N^p\rangle/\langle N\rangle^p$ are pure numbers, independent of any of the physical parameters of the problem. We recognize a special negative binomial distribution which is characterized by large statistical fluctuations. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry.

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