相对论重离子碰撞中背景的选取对2π干涉学分析的影响

用小相对动量区域2π干涉学分析方法,研究了相对论重离子碰撞中背景的选取对2π干涉学分析所得π源参数的影响,得到了在不同背景下2π干涉学分析所得π源参数之间的解析关系,与相对论重离子中心碰撞1.8A GeV Ar+Pb的实验结果进行了对比.     

相对论非对称重离子碰撞中小相对动量区域2π干涉学

用小相对动量区域2π干涉学分析方法研究了相对论非对称重离子碰撞中π介子的吸收存在时对2π干涉学分析所得π源参数的影响,得到了不考虑和考虑π的吸收情况下所得到的源的参数的解析关系.与相对论非对称重离子碰撞1.8A GeVAr+Pb的实验结果进行了对比.     

Multiplicity dependence of the pion source in S+A collisions at the CERN SPS

The emission of pions from relativistic heavy-ion collisions of S+S, S+Ag and S+Pb at 200 GeV/nucleon is characterized using two-particle interferometry. The multiplicity dependence of the pion source parameters near midrapidity is studied. The transversal (R _t) and longitudinal (R _l) pion source parameters are independent of the initial nuclei in the interaction and increase with increasing multiplicity. This suggests that the freeze-out process is governed mainly by the particle multiplicity. The multiplicity dependence is weaker than that expected from a simple model of a freeze-out at a constant density.     

Determining pion source parameters in relativistic heavy-ion collisions

Two-pion inclusive spectra from relativistic heavy-ion collisions are related to single-particle inclusive measurements in a Lorentz-invariant formulation of the Hanbury-Brown-Twiss effect. A thermal pion source with a gaussian space-time distribution is assumed. The angular anisotropy and moments of the correlation function are computed to facilitate the determination of pion source parameters from the ratios of the two-pion to single-pion inclusive data.     

Two-pion interferometry at small relative momentum for pion sources with transverse and longitudinal expansions in relativistic heavy ion collisions

A two-pion correlation function at small relative momentum for pion sources with transverse and longitudinal expansions in relativistic heavy ion collisions is obtained using two-pion interferometry at small relative momentum, and the relations between the real and apparent parameters of the pion source are given. The relations can be used to extract both the temperature and the transverse and longitudinal expansion velocities of pion sources and to verify the correctness of relativistic transformation T′=T\sqrt {1-v^2} of temperature in relativistic statistical mechanics and thermodynamics.     

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.     

相对论重离子碰撞中部分相干源的相干因子

给出了两种统计系综下相对论重离子碰撞中部分相干源的相干因子的表达式     

Two-Pion Interferometry at Small Relative Momentum Taking Account for Multi-Pion Correlations

A general expression for nπ correlation function is given when there are multi-pion correlations in the choices of correlated nπ and uncorrelated nπ. Using this expression, the two-pion interferometry at small relative momentum which takes account for multi-pion correlations is studied, the relations between the pion source parameters from the two-pion interferometry and the three- pion interferometry are obtained analytically, and comparison is made with the experimental results of central relativistic heavy ion collisions 1.8 A GeV Ar+Pb.     

Three-pion correlations for studying partial coherence in nuclear collisions

Use of three-particle correlations provides a unique tool for studying partial coherence in relativistic heavy-ion collisions. Here a theory is presented for multiple coherent source components of partially coherent pion radiation. Results are given for the relative probabilities of emission of one, two, or three pions. The calculations on the relation between two- and three-pion correlators give some evidence, when compared with available experimental data, for the existence of partial coherence and multiple coherent components in heavy-ion collisions.     

柱形夸克胶子等离子体的2π干涉学检测

在2п干涉学中,对不同的п源2п,关联函数可以是不同的. 如果在相对论重离子碰撞中出现柱形夸克胶子等离子体,п介子将从柱形夸克胶子等离子体表面发射,此时2п关联函数将出现一种特殊的振荡行为.这种振荡行为可以用来探明夸克胶子等离子体的存在性,同时也是相对论重离子碰撞中出现夸克胶子等离子体的一个信号.     

Test of Quark-Gluon Plasma of Cylinder Shape by Two-Pion Interferometry

The two-pion correlation functions are different for some pion source distributions in two-pion interferometry.If quark-gluon plasma of cylindrical shape is produced in relativistic heavy ion collisions, the pion mesons will emit from the surface of quark-gluon plasma of cylindrical shape and the corresponding correlation function will have a special oscillation behavior. The oscillation behavior can be used to verify the existence of quark-gluon plasma and is also a signature of the appearance of quark-gluon plasma.     

超相对论重离子碰撞中小相对动量区域2π干涉学

用小相对动量区域π干涉学方法给出了超相对论重离子碰撞中两种模型下π源参数的关系,并与200A GeV O+Au碰撞的实验结果进行了对比.     

Pion collectivity in relativistic heavy-ion collisions

The inelastic nucleon-nucleon cross section may be enhanced in the nuclear medium by pion collectivity. Empirical hamiltonians are on the borderline of strongly collective behavior, and the predicted enhancement factors range from 1–5 for various hamiltonians from the literature. An enhancement would have a substantial effect on the sideward flow in relativistic heavy-ion collisions. If this effect is present, the equation of state could be softer than in previous analyses.     

非静态球形夸克-胶子等离子体的2π干涉学的检测

提出了一种相对论重离子碰撞中强子物质生成时的π膨胀源模型. 得到了该模型中的小相对论动量区域的2π关联函数及表观π源参数R_a与实际π源参数R_e的关系. 这一关系与QGP生成时的关系有所区别. 这一区别可以用来检测相对论重离子碰撞中产生的非静态球形夸克-胶子等离子体的存在性. 两个关系也显示了一种标度行为.     

In-plane elliptic flow of resonance particles in relativistic heavy-ion collisions

We analyze the second Fourier coefficient v(2) of the pion azimuthal distribution in noncentral heavy-ion collisions in a relativistic hydrodynamic model. The exact treatment of the decay kinematics of resonances leads to almost vanishing azimuthal anisotropy of pions near the midrapidity, while the matter elliptic flow is in plane at freeze-out. In addition, we reproduce the rapidity dependence of v(2) for pions measured in noncentral Pb+Pb collisions at 158A GeV. This suggests that resonance particles as well as stable particles constitute the in-plane flow and are important ingredients for the understanding of the observed pion flow.     

The inversion-asymmetry of particle emission source in relativistic heavy-ion collisions

The inversion-asymmetry of the particle emission source in relativistic heavy-ion collision under the Bertsch-Pratt convention is discussed and explicitly exhibited by a Monte Carlo model. The Gaussian source function popularly used in the HBT analysis of relativistic heavy-ion collisions is invalid in this case. An inversion-asymmetric source function is suggested. A method for extracting the inversion-asymmetry degree of the source together with the source size from experimental data is proposed.     

Shadowing effect on pion spectra from intermediate-energy heavy-ion collisions

Pion spectra from asymmetric heavy-ion collisions at intermediate energies are studied in the slab geometry. The effect of pion absorption is treated in a phenomenological way. The shadowing of outgoing pions explains the apparent velocity of “the pion emitting source”.     

HBT参数对π源空间分布的敏感性研究(英文)

利用理想高斯源的两粒子关联函数，对单高斯源和双高斯源的两π介子HBT关联效应进行了研究，得出了相应的半径参数和A参数．结果表明，半径参数主要取决于高能重离子碰撞中多数π介子产生的中间区域；对产生π介子的边缘区域的空间分布形状不敏感．在边缘区域内产生的π介子主要影响A参数的变化．π介子源空间分布的非高斯形是导致λ参数减少的一个重要因素．The HBT radius parameters and the HBT λ-parameters of single Gaussian source and double Gaussian source are investigated by using two-pion correlation function in HBT intensity interferometry. It is indicated that the radius parameter is insensitive to the spatial shape of the edge zone of source and is mainly affected by the size of the central zone of pions emitted in high energy heavy-ion collisions. The pions produced at the edge of source influence the λ parameter. The non-Gaus...     

Pion chemical potentials in heavy-ion collisions: relativistic quantum molecular dynamic analysis

In the framework of relativistic quantum molecular dynamics we analyse pion chemical potentials in the hadron system produced in central heavy-ion collisions at the bombarding energiesE _lab/A=(1–2) GeV/nucl. We find that the equilibrium relations hold for chemical potentials of π^?, of π⁰, of π⁺ and pion energy spectra reach local thermal equilibrium. However, there is no chemical equilibrium. The pion chemical potentials are very large and decrease during the expansion stage.