Centrality and Transverse Momentum Dependencies of Minijets and Hadrons in Au-Au Collisions
Centrality and Transverse Momentum Dependencies of Minijets and Hadrons in Au-Au Collisions
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DOI：
10.1103/physrevc.88.044919
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发表时间：
2013-07
影响因子：
3.1
通讯作者：
Lilin Zhu;R. Hwa
中科院分区：
文献类型：
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作者：
Lilin Zhu;R. Hwa
在RHIC上Au-Au碰撞强子产生的研究中，微喷注在产生中间ppt区的簇射部分子中起着重要作用。当硬部分子和半硬部分子以不同的方位角穿过非均匀介质时，它们的动量退化会导致几何、核和动力学因素的复杂卷积，通常无法以透明的方式描述。在这项工作中，发现一个紧凑的公式，表示在任何碰撞中心的介质表面的任何部分子类型的微型喷流的包容性分布。它们考虑了在介质中任何一点产生的所有初始部分子的贡献。通过与无能量损失的情况比较，确定了一个类似于微型射流核修正因子的比值。这种分布的唯象现实检查通过计算强子化的重组模型中的微喷流。通过调整控制热部分子大小和半硬部分子降解速率的参数，得到了与π介子、K介子和质子产生的数据的良好拟合。这一结果一方面支持了任意中心度的小喷注谱，另一方面也支持了强子化过程。在这项研究中表现出的一个重要性质是，夸克和胶子必须以不同的方式失去能量，因为部分子通过重组形成介子和重子的方式不同，夸克和胶子的动量必须以不同的速率退化，以重现实验的π介子和质子谱。这是一个使部分子-强子对偶概念或其他基于类似思想的强子化方案无效的特征。
In the study of hadron production in Au-Au collisions at RHIC minijets play an important role in generating shower partons in the intermediate \ppt\ region. Momentum degradation of the hard and semihard partons as they traverse the inhomogeneous medium at various azimuthal angles results in a complicated convolution of geometrical, nuclear and dynamical factors that cannot usually be described in a transparent way. In this work a compact formula is found that represents the inclusive distributions of minijets of any parton type at the surface of the medium for any collision centrality. They take into account the contributions from all initiating partons created at any point in the medium. By comparing with the case of no energy loss, a ratio has been determined that is analogous to the nuclear modification factor for minijets. Phenomenological reality of such distributions is examined by calculating the hadronization of the minijets in the recombination model. Good fits of the data on pion, kaon and proton production throughout the intermediate \ppt\ region have been obtained by adjusting the parameters controlling the magnitude of the thermal partons and the degradation rates of the semihard partons. The result gives support to the minijet spectra at any centrality on the one hand, and the hadronization procedure used on the other. An important property made manifest in this study is that quarks and gluons must not lose energy in the same way because the partons form mesons and baryons differently by recombination and the momenta of quarks and gluons must be degraded at different rates in order to reproduce the experimental pion and proton spectra. This is a feature that renders invalid the notion of parton-hadron duality or other hadronization schemes based on similar ideas.