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arXiv 1902.11290nucl-thnucl-ex
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小碰撞系统中流动和非流动分解方法的检验

Examination of Flow and Non-Flow Factorization Methods in Small Collision Systems

S. H. Lim, Q. Hu, R. Belmont, K. K. Hill, J. L. Nagle, D. V. Perepelitsa

备注：
27 pages, 28 figures
发表信息：
Phys. Rev. C 100, 024908 (2019)
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摘要：

两粒子关联已被广泛用于研究重离子碰撞中的流体动力学流态。在小碰撞系统中，例如$p$ $+$ $p$和$p$ $+$ $A$，其中粒子多重性比在$A$ $+$ $A$碰撞中小得多，来自喷流相关性、动量守恒、粒子衰变等的非流动效应可能是显著的，即使在粒子之间施加大的赝快度间隙时也是如此。通过在大型强子对撞机（LHC）上的实验，发展了一系列扣除两粒子关联中非流贡献的技术，并用于测量$p$ $+$ $p$和$p$ $+$ Pb碰撞中的粒子流。最近，在相对论重离子对撞机（RHIC）的实验已经探索了在较低能量的小型碰撞系统中采用这些技术的可能性。在本文中，我们测试这些技术使用Monte Carlo生成器PYTHIA和HIJING，其中不包括任何集体流，和AMPT，这是。我们发现，这是至关重要的，以检查这样的测试结果的相关性集成在粒子的横向动量$p_T$和差分作为$p_T$的功能。我们的结果表明，合理的非流扣除$p$ $+$ $p$碰撞在最高的LHC能量，而失败，如果应用于$p$ $+$ $p$碰撞在RHIC。在RHIC的$p$ $+$ Au碰撞的情况下，HIJING和AMPT结果都表明$p_{T}\gtrsim1~{\rm GeV}/c$的非流动的大量过度扣除，因此低估了椭圆流。

英文摘要：

Two particle correlations have been used extensively to study hydrodynamic flow patterns in heavy-ion collisions. In small collision systems, such as $p$$+$$p$ and $p$$+$$A$, where particle multiplicities are much smaller than in $A$$+$$A$ collisions, non-flow effects from jet correlations, momentum conservation, particle decays, etc. can be significant, even when imposing a large pseudorapidity gap between the particles. A number of techniques to subtract the non-flow contribution in two particle correlations have been developed by experiments at the Large Hadron Collider (LHC) and then used to measure particle flow in $p$$+$$p$ and $p$$+$Pb collisions. Recently, experiments at the Relativistic Heavy Ion Collider (RHIC) have explored the possibility of adopting these techniques for small collision systems at lower energies. In this paper, we test these techniques using Monte Carlo generators PYTHIA and HIJING, which do not include any collective flow, and AMPT, which does. We find that it is crucial to examine the results of such tests both for correlations integrated over particle transverse momentum $p_T$ and differentially as a function of $p_T$. Our results indicate reasonable non-flow subtraction for $p$$+$$p$ collisions at the highest LHC energies, while failing if applied to $p$$+$$p$ collisions at RHIC. In the case of $p$$+$Au collisions at RHIC, both HIJING and AMPT results indicate a substantial over-subtraction of non-flow for $p_{T}\gtrsim1~{\rm GeV}/c$ and hence an underestimate of elliptic flow.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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