Eccentricity and elliptic flow at fixed centrality in Au+Au collisions at √<SPAN style=

In this paper, elliptic flow is studied at fixed centrality in Au+Au collision at √s_NN=200 GeV in the AMPT model. It is observed that with the participant increasing, elliptic flow has an increase or a decrease at different fixed impact parameter, but it does not have a trivial fluctuation. It is analyzed that the initial space anisotropy dominates the participant dependence of elliptic flow in near-central collisions(b=5 fm) and mid-central collisions(b=8 fm), while the interaction between particles can mainly answer for the behavior of elliptic flow with participant in peripheral collisions (b=12 fm). To distinguish the pure geometrical effect, elliptic flow scaled by initial eccentricity is studied. It is found that the ratio v₂/ε increases with participant and reaches a saturation when the participant is large enough, indicating that the collision system may reach the local equilibrium.     

Critical behavior of higher cumulants of order parameter in the 3D-Ising universality class

QCD deconfinement phase transition is supposed to be the same universality class as the 3D-Ising model. According to the universality of critical behavior, the Binder-like ratios and ratios of higher cumulants of order parameter near the critical temperature in the 3D-Ising model are studied. The Binder-like ratio is shown to be a step function of temperature. The critical point is the intersection of the ratios of different system sizes between two platforms. The normalized cumulant ratios, like the Skewness and Kurtosis, do not diverge with correlation length, contrary to the corresponding cumulants. Possible applications of these characters in locating critical point in relativistic heavy ion collisions are discussed.     

不同快度窗口中带电多重数的奇、偶分布及归一化矩的能量依赖性

本文从一个简单的具有非零电荷关联长度的物理图象出发,计算了强子-强子碰撞在不同快度窗口中的奇、偶带电多重数分布,解释了这些分布的重合和分开.计算得到的规一化矩的窗口依赖性和能量依赖性与实验一致.引进了一种新的、特别适合于小快度窗口的归一化矩.     

多重数矩的能量依赖性与三火球模型

本文分析了√s=11.5GeV到900GeV的12个能量下的多重数矩的实验数据, 指出三火球模型的计算结果和这些数据符合得很好, 发现侧边火球的平均大小随能量的变化有两个平台.     

在高能碰撞低多重数事件中用阶乘矩方法研究混沌时统计起伏的主导作用

用MonteCarlo模拟证明了 ,在低多重数事件中 ,单事件阶乘矩被统计起伏饱和 .实验中观察到的“单事件矩的事件空间矩” C_{p ,q}随相空间标度减小的散开 (称为“无规性”) ,很容易用只包含统计起伏的平坦几率分布重现 ,因而和想象的不一样 ,不能表明是否存在混沌 .讨论了在高多重数事件中用“无规性”研究混沌的可能性 .     

Finite-size behaviour of generalized susceptibilities in the whole phase plane of the Potts model

We study the sign distribution of generalized magnetic susceptibilities in the temperature-external magnetic field plane using the three-dimensional three-state Potts model. We find that the sign of odd-order susceptibility is opposite in the symmetric(disorder) and broken(order) phases, but that of the even-order one remains positive when it is far away from the phase boundary. When the critical point is approached from the crossover side, negative fourth-order magnetic susceptibility is observable. It is also demonstrated that non-monotonic behavior occurs in the temperature dependence of the generalized susceptibilities of the energy. The finite-size scaling behavior of the specific heat in this model is mainly controlled by the critical exponent of the magnetic susceptibility in the three-dimensional Ising universality class.     

高能核子-核子和核-核碰撞中电荷起伏的测量

利用强子-强子碰撞的模型PYTHIA以及核-核碰撞的模型RQMD比较了各种电荷起伏测量量的快度依赖性，结果发现，这些测量量对快度的依赖性依赖于模型. 但是，电荷关联能很好地测量整体电荷守恒以及短程快度关联性质. 因此，被认为是一个好的反应电荷起伏的测量量.     

Source Function Determined from Hanbury—Brown／Twiss Correlations by the Maximum Entropy Principle

We study the reconstruction of the source function in space-time directly from the measured Hanbury-Brown/Twiss (HBT) correlation function using the maximum entropy principle.We find that the problem is ill-defined without at least one additional theoretical constraint as input.Using the requirement of a finite source lifetime for the problem we find a new Gaussian parametrization of the source function directly in terms of the measured HBT radius parameters and its lifetime,where the latter is a free parameter which is not directly measurable by HBT.We discuss the implication of our results for the remaining freed om in building source models consistent with a given set of measured HBT radius parameters.     

强子–强子碰撞中硬分量存在的又一实验证据

对sqr(s)=540Gev能量下的高能强子-强子碰撞得到的单事件平均横动量p. 对多重数N的散点图进行了仔细分析后指出;其中大多重数、大事件是碰撞过程中出现硬分量的又一个实验证据,并用仅含软分量的单分量模型和既含软分量又含硬分量的二分量模型的Monte Carlo模拟定性地证实了这一论断.     

阶乘矩的归一化与间歇指数对平均横动量的依赖性

本文对阶乘矩的两种不同归一化进行了细致的分析,发现在固定多重数以及间歇程度不依赖于多重数的情况下,两种归一化得到的间歇指数相等.对于多重数不固定,而间歇程度与多重数有关的情况,给出了两种不同归一化得到的间歇指数用动力学间歇指数表示的公式.本文还在间歇程度依赖于单事件平均横动量的假定下,全面复现了实验上观察到的间歇对横动量截断的依赖性,证实了平均横动量对于决定间歇程度有重要意义.