Energy Dependance of Azimuthal Correlations (and more) in Nucleus-Nucleus Collisions at the CERN SPS
Marek Szuba
备注：
9 pages, 7 figures. To appear in the proceedings for 5th International Workshop on Critical Point and Onset of Deconfinement (CPOD), 2009.06.08-12, Brookhaven National Laboratory
Analysing two-particle azimuthal and pseudorapidity-azimuth correlations of high-pT hadrons, experiments at the RHIC have obtained results - "the double hump", "the ridge" etc. - which provide interesting information about properties of the hot, dense medium produced in central high-energy heavy-ion collisions as well as of its interaction with products of hard scattering. However, not all of the observed effects have been fully explained by theory or models yet; such explanations are hampered in part by the lack of good reference from lower collision energies. In an attempt to further our understanding of angular dihadron correlations NA49 has, as one of the first experiments at the SPS, performed a number of scans of these correlations in Pb+Pb, Si+Si and p+p collisions at sqrt(sNN) = 17.3 GeV, as well as central Pb+Pb collisions at sqrt(sNN) = 12.3, 8.8, 7.6 and 6.3 GeV. Results of these scans have been compared to UrQMD simulations. Our experimental results from two-particle azimuthal correlations show a flattened away-side peak in central Pb+Pb (Au+Au) collisions, only weakly depends on collision energy over the whole investigated energy range - suggesting this effect originates from sources other than jet-medium interactions. This hypothesis is reinforced by good agreement with UrQMD regardless of whether jet production was enabled in the model or not. On the other hand, the amplitude of the near-side peak in central Pb+Pb (Au+Au) collisions drops visibly with decreasing collision energy, flattening out around sqrt(sNN) = 8.8 GeV and turning into a depletion below that energy - possibly an effect related to the onset of deconfinement. Finally, hints of the ridge structure can be observed in pseudorapidity-azimuth correlation functions from central Pb+Pb collisions at sqrt(sNN) = 17.3 GeV.
A new heavy-ion experiment on fixed target, NA60+, has been proposed at the CERN SPS for data taking in the next years. Its main goals will be focused on precision studies of thermal dimuons, heavy quark and strangeness production in Pb-Pb collisions at center-of-mass energies ranging from 5 to 17 GeV, which will provide a unique opportunity to investigate the region of the QCD phase diagram at high baryochemical potential ($μ_B \sim 200-400$~MeV). The key points of the NA60+ very broad and ambitious physics program will be described.
Energy dependence of hadron spectra and yields in p+p and $^7$Be+$^9$Be collisions from the NA61/SHINE experiment at the CERN SPS
NA 61/SHINE关于强相互作用的方案包括研究解除封闭的开始，目的是通过在欧洲核子研究中心的整个SPS动量范围内进行能量和系统大小的扫描，发现强相互作用物质的临界点。到目前为止，已经完成了p+p，$^7$ Be+ $^9$ Be，以及Ar+Sc的扫描。从p+p和Be+Be碰撞的结果现在出现，特别是强子谱和产额的能量依赖性。将介绍这一努力的现状和初步结果。
Pion production in p+p interactions and Be+Be collisions at the CERN SPS energies
NA 49在束流动量为30 A GeV/c的固定靶测量中报告了中心Pb+Pb碰撞中解除禁闭开始的证据。这一观察激发了2009年在CERN SPS启动的NA 61/SHINE计划，该计划特别旨在通过测量质子-质子，质子-核和核-核碰撞中的强子产生来研究解除禁闭的开始特性。本文给出了在20 A-158 A GeV/c束流动量下p+p相互作用和$^7$ Be+ $^9$ Be碰撞中产生的带电π介子的谱。在相同的束流动量下，将NA 61/SHINE的计算结果与相应的NA 49的Pb+Pb中心碰撞数据进行了比较。
Onset of Deconfinement in Pb+Pb Collisions at the Cern SPS
NA 49固定靶实验研究了在CERN SPS的核-核反应中产生的高能量密度物质。在158 AGeV的中心Pb+Pb碰撞中，早期的能量密度大大超过了格点量子色动力学预言的夸克退禁闭阈值.产生的物质表现出强烈的横向和纵向流动。所产生的颗粒的产率的比率大致符合统计平衡。通过SPS范围内的能量扫描显示结构的能量依赖的π介子和K介子的产量以及横向质量分布的反斜率。这些特征表明，在中心Pb+Pb碰撞中，在30 A GeV左右开始产生退精细相。对涨落和相关性的分析还没有为QCD的临界点提供证据。
Energy dependence of fluctuations in central Pb+Pb collisions from NA49 at the CERN SPS
NA 49的最新结果的多重数和平均横向动量的波动分析的事件的基础上，提出了在整个SPS能量范围（20 A-158 A GeV）的中心Pb+Pb相互作用。多重性分布的标度方差随碰撞能量而减小，而$<p_T>$波动的$Φ_{p_{T}}$测量是小的并且与碰撞能量无关。因此，在中心Pb+Pb碰撞中，这些波动并不表明强相互作用物质的临界点。
NA61/SHINE at the CERN SPS: plans, status and first results
NA 61/SHINE实验旨在发现强相互作用物质的临界点，并研究解除禁闭开始的性质。它还为中微子和宇宙射线实验进行精确的强子产生测量。这些目标将通过测量强子在核-核、质子-质子和质子-核相互作用中的产生特性作为碰撞能量和碰撞核大小以及π-核相互作用的函数来实现。这篇文章总结了离子计划的论点，并介绍了NA 61实验的第一个物理结果。
The high-$μ_{\rm B}$ region of the QCD phase diagram has become the object of several studies, focused on the investigation of the order of the phase transition and the search for the critical point. Accessing rare probes is experimentally challenging as it requires large integrated luminosities, and a fixed-target environment represents an ideal solution for these studies. The CERN SPS covers, with large beam intensity, the collision energy region $5<\sqrt{s_{\rm NN}}<17$ GeV. A future experiment, NA60+, is being proposed to access this region and perform accurate measurements of the dimuon s…
Status and plans of the ion program of NA61 at the CERN SPS
NA 61/SHINE是研究p+p p+A、h+A和A+A相互作用中强子产生的新实验。NA 61离子计划的主要目标是探索强相互作用物质的相图（T-mu_B）。特别是，我们计划研究的性质的开始解除限制，并寻找签名的临界点。通过改变碰撞的能量（13 A-158 A GeV）和系统尺寸（p+p，Be+Be，Ar+Ca，Ar +La）来进行相图的二维扫描。本文概述了NA 61/SHINE离子计划的现状和计划。特别是探测器升级，数据采集时间表和光谱和相关性的第一个结果进行了讨论。
NA61/SHINE results on fluctuations and correlations at CERN SPS energies
NA 61/SHINE强相互作用计划的目的是探索强相互作用物质的相图。主要的物理学目标是研究解除禁闭的开始和寻找强相互作用物质的临界点。通过执行束流动量（13 A- 150/158 A GeV/c）和系统尺寸（p+p、p+Pb、Be+Be、Ar+Sc、Nd +La、Pb+Pb）扫描来追求这些目标。这一贡献提出了新的结果NA 61/SHINE波动和相关性，其中包括特别是量子相关性，以及多重性和净电荷波动，质子密度波动和各向异性集体流。所得结果与其他实验和模型预测进行了比较。
Lambda production in central Pb+Pb collisions at CERN-SPS energies
本文介绍了在40、80和158 A $\cdot$ GeV的中心Pb+Pb碰撞中产生的$Λ$和$\barΛ$超子的NA 49实验的最新结果。横向质谱和快度分布的$Λ$显示为所有三种能量。随着束流能量的增加，快度分布的形状变得更平坦。在中快度的多重性以及总产量作为碰撞能量的函数，包括AGS测量研究。中快度和4 $π$中的$Λ/π$比在40 A $\cdot$ GeV左右有一个最大值。此外，$\barΛ$快度分布已被测量在40和80 A $\cdot$ GeV，这允许研究的$\barΛ$ / $Λ$的比例。
Transverse Momentum and Multiplicity Fluctuations in Ar+Sc Collisions at the CERN SPS from NA61/SHINE
NA 61/SHINE实验旨在发现强相互作用物质的临界点，并研究解除禁闭开始的性质。为了实现这些目标，正在SPS上通过测量质子-质子、质子-原子核和原子核-原子核相互作用中强子的产生作为碰撞能量和系统尺寸的函数，对二维相图（$T$ - $μ_{B}$）进行扫描。在这方面的贡献的初步结果表示的横向动量和多重性波动的强烈密集的数量从Ar+Sc的能量扫描。预计这些波动对临界点的存在很敏感。的结果进行了比较，从p+p和Be+Be能量扫描的结果，以及与NA 49测量。
The NA61/SHINE strong interaction programme aims to explore the phase diagram of the strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of the strongly interacting matter. These goals are pursued by performing a scan in beam momentum (13A -- 158A GeV/c) and size of colliding system (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). This contribution presents new results on system size and energy dependence of multiplicity and net-charge fluctuations measured with higher-order moments of these distributions. Also, new resu…
NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong interactions program are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. To reach these goals, hadron production measurements are performed in the form of a two-dimensional scan by varying collision energy and system size. The Collaboration has recently finished data acquisition for its original program on strong interactions, accumulating broad data samples on hadron production in various systems …
Transverse momentum and multiplicity fluctuations in Ar+Sc collisions at the CERN SPS from NA61/SHINE
NA 61/SHINE实验旨在发现强相互作用物质的临界点，并研究解除禁闭开始的性质。为了实现这些目标，正在SPS上通过测量质子-质子、质子-原子核和原子核-原子核相互作用中强子的产生作为碰撞能量和系统尺寸的函数，对二维相图（$T$ - $μ_{B}$）进行扫描。在这方面的贡献的初步结果表示的横向动量和多重性波动的强烈密集的数量从Ar+Sc的能量扫描。预计这些波动对临界点的存在很敏感。的结果进行了比较，从p+p和Be+Be能量扫描的结果，以及与NA 49测量。
