用各向异性流v2和v4测试超相对论性重离子碰撞的动力学描述

We present various predictions for the anisotropic collective flow of particles in heavy-ion collisions, in particular scaling laws of the second and fourthharmonics v₂ and v₄, derived within ideal fluid dynamics. We also discuss qualitatively the deviation from the ideal behaviour expected in an out-of-equilibrium scenario.     

An Explanation of a Phenomenon in Relativistic Heavy-Ion Collisions

The multi-source pion interferometry in relativistic heavy-ion collisions is presented and two-source models for hadron gas and hadron gas plus quark-gluon plasma are proposed. The models can resolve the HBT puzzle. For the same $q$ and different direction of \bar{q}, the two-pion correlation functions show characteristic oscillation behaviors, which may be used to distinguish the two-source models. Our research also showes that the multi-source pion correlations can resolve the HBT puzzle.     

在重离子碰撞中的K－介子吸收对其产生的影响

用RBUU方法研究了中高能重离子碰撞中K^－介子产额及谱的情况.我们发现K⁺/K^－产额比是与核系统大小相关的,这种相关性与K^－介子在核介质中所受的吸收效应有关.还研究了在三种不同核系统中的K^－平均吸收路程,发现K^－平均吸收路程在轻核系统中与在中、重核系统中存在较大的差别,从而定量地解释了这种K⁺/K^－比与核系统的相关性.研究结果给出了核介质对K^－介子的吸收程度还与不同反应道的贡献有关,这是导致Bπ→K^－X道在核系统,特别是在轻、中量核系统中起重要作用的一个重要原因.     

重离子碰撞中的K介子流

用量子分子动力学(QMD)模型研究了中能重离子碰撞中的K⁺介子流. 计算结果显出, 实验数据只能与计入由手征拉格朗日导出的K⁺平均场势的结果相符合.这表明, K⁺介子边流的形式是对在核介质中K⁺位势的一个有效的探针.     

Net-Baryon and Net-Kaon Rapidity Distributions in Ultrarelativistic Heavy-Ion Collisions

In this paper, the gluon distribution is extracted from the KLR-AdS/CFT saturation model and used to investigate net-baryon and net-kaon rapidity distributions in ultrarelativistic heavy-ion collisions. With the same parameters of the saturation model fitting to HERA data and an χ² analysis of the overall constant C, the theoretical results are in good agreement with RHIC data in Au+Au collisions at √s=0.2 TeV. Then, we present the predictive results for net-baryon rapidity distributions in central Pb+Pb collisions at LHC energies of √s=2.76, 3.94, and 5.52 TeV, and give the corresponding values of d N/d y for net-baryon at y=0.     

A New Explanation for e+e- Puzzle in Heavy-Ion Collisions

A dielectric model for the QED vacuum in a strong nuclear environment is proposed to explain the e⁺e^- puzzle in heavy-ion collisions, the agreement with experiment is satisfactory. New experiment is suggested from this model.     

RHIC能区Au+Au碰撞中集合径向流的研究

利用相对论量子分子动力学模型RQMD,对RHIC能区s=200A GeV Au+Au碰撞的集体膨胀效应进行了研究,对散射粒子的横质量谱进行了分析.研究表明,在RHIC能区的重离子反应中存在有强的集合径向流.对单粒子谱的拟合结果给出Au+Au的源冻结温度为160MeV,平均径向流速度为0.6c.     

用第一级反应平面测量重离子碰撞中逐事件椭圆流涨落的一种方法

A new method is presented for measuring event-by-event fluctuations of elliptic flow (v₂) using first-order event planes. By studying the event-by-event distributions of v₂ observables and first-order event-plane observables, average flow 〈v₂〉and event-by-event fluctuations with respect to that average can be separately determined, making appropriate allowance for the effects of finite multiplicity. The relation of flow fluctuations to eccentricity fluctuations in the initial-state participant region, as well as detector acceptance effects, are discussed.     

Heavy-Ion Collisions toward High-Density Nuclear Matter

In the present paper, the current efforts in heavy-ion collisions toward high-density nuclear matter will be discussed. First, the essential points learned from RHIC and LHC will be reviewed. Then, the present data from the STAR Beam Energy Scan are discussed. Finally, the current efforts, NICA, FAIR, HIAF, and J-PARC-HI (heavy ion) are described. In particular, the efforts of the J-PARC-HI project are described in detail.     

Hard Probes 2010: Experimental summary

A (personal) experimental summary of the Hard Probes 2010 conference is presented.     

RHIC能区Au+Au碰撞中HBT关联参数分析

利用相对论量子分子动力学模型RQMD,对RHIC能区s=200GeV/u Au+Au碰撞进行了2π干涉学分析,并讨论了HBT半径参数对横动量的依赖关系.研究表明,两粒子关联函数能够给出碰撞源在冻结时刻的时空拓扑信息,HBT半径参数能够较好地反映源的尺度和形状,但其对横动量的依赖关系并不能直接反映源的压缩性质,而是对粒子产生时源的空间–动量关联程度更为敏感.     

RHIC能区Au+Au碰撞中椭圆流的横半径依赖

用RQMD模型模拟了质心系束能量为s_NN=200GeV的Au+Au非对心碰撞, 研究了椭圆流对末态粒子冻出位置的关系. 研究表明, 随着冻出半径的增加, 椭圆流逐渐增强, 在源的初始表面处达到最大值, 随着冻出半径的继续增加, 椭圆流逐渐减小. 椭圆流的这种变化趋势反映了随着半径的增加, 压力梯度在各个方向上不同的变化. 本文提出了利用平均径向速度分析压力梯度的方法.     

Investigation of experimental observables in search of the chiral magnetic effect in heavy-ion collisions in the STAR experiment

The chiral magnetic effect(CME)is a novel transport phenomenon,arising from the interplay between quantum anomalies and strong magnetic fields in chiral systems.In high-energy nuclear collisions,the CME may survive the expansion of the quark-gluon plasma fireball and be detected in experiments.Over the past two decades,experimental searches for the CME have attracted extensive interest at the Relativistic Heavy Ion Collider(RHIC)and the Large Hadron Collider(LHC).The main goal of this study is to investigate three pertinent experimental approaches:the$\gamma$correlator,the R correlator,and the signed balance functions.We exploit simple Monte Carlo simulations and a realistic event generator(EBE-AVFD)to verify the equivalence of the core components among these methods and to ascertain their sensitivities to the CME signal and the background contributions for the isobar collisions at the RHIC.     

超相对论Au+Au碰撞中椭圆流的时间依赖

用相对论量子分子动力学(RQMD)模型模拟了质心系束能量为s_NN=200GeV的Au+Au非对心碰撞, 研究了椭圆流对末态粒子冻出时间的关系. 研究了在不同的阶段, 椭圆流对末态粒子位置的关系. 结果表明椭圆流随冻出时间的单调递减, 椭圆流对横向半径的关系随冻出时间发生变化. 用压力梯度对所得结果进行了分析. 径向速度用来表征压力梯度.     

Bose-Einstein Correlation of Kaon Pairs from Heavy-Ion Collisions at CERN Energy

The Bose-Einstein correlation of kaons from 160A GeV/c Pb + Pb collisions is analyzed within an event generator UR4SiMA. The theoretical results are in agreement with the preliminary data of NA44.     

Finite-Size Effects on the Phase Diagram and Evolution of Strangelets in Ultrarelativistic Heavy-Ion Collisions

In the framework of multiple reflection expansion, finite-size effects are incorporated into the study of the phase diagram and evolution of a strangelet in equilibrium with a finite hadronic phase. It is found that in a significant way finite-size effects can modify the phase diagram and reduce the survival probabilities of cold strangelets in ultrarelativistic heavy-ion collisions. The inclusion of finite-size effects can also allow a quantitative analysis of the properties of a cold strangelet resulting from a smooth hydrodynamic evolution with equilibrium hadronization and isentropic expansion.     

Elliptic flow at SPS and RHIC: from kinetic transport to hydrodynamics

Anisotropic transverse flow is studied in Pb+Pb and Au+Au collisions at SPS and RHIC energies. The centrality and transverse momentum dependence at midrapidity of the elliptic flow coefficient v₂ is calculated in the hydrodynamic and low density limits. Hydrodynamics is found to agree well with the RHIC data for semicentral collisions up to transverse momenta of 1–1.5 GeV/c, but it considerably overestimates the measured elliptic flow at SPS energies. The low density limit LDL is inconsistent with the measured magnitude of v₂ at RHIC energies and with the shape of its p_t-dependence at both RHIC and SPS energies. The success of the hydrodynamic model points to very rapid thermalization in Au+Au collisions at RHIC and provides a serious challenge for kinetic approaches based on classical scattering of on-shell particles.     

用动力学夸克并合描述RHIC重离子碰撞中和各相异性流和它们的标度率

We report the results on anisotropic flows and their scaling forφmesons andΩ(Ω~- ■~ )baryons in Au Au collisions at RHIC,obtained from a dynamical quark coalescence model that uses the quark phase- space information from a multi-phase transport(AMPT)model within the string melting scenario and includes the quark structure of hadrons.     

相对论重离子碰撞中π源密度分布和小相对动量区域2π干涉学分析

用2π关联函数在小相对动量区域的幂级数展开,得到了不同π源密度分布下源的空间参数、平均半径和均方根半径间关系,与相对论重离子中心碰撞1.8A GeV Ar+Pb的实验结果一致. 给出了上述反应中π源的平均半径和均方根半径.对不同的源密度分布,计算了K_t的值.