S=1800GeV pp碰撞荷电粒子多重性分布的计算

假设高能强子—强子碰撞的多重性分布中,软相互作用部分和硬相互作用部分都服从KNO无标度性,只是它们各自的参数不同.由已有的实验数据,计算出S=188GeV处,碰撞的平均多重性=47.0及其荷电粒子的多重性的分布.可供实验检验.     

＝1800GeV pp碰撞荷电粒子多重性分布的计算

假设高能强子—强子碰撞的多重性分布中，软相互作用部分和硬相互作用部分都服从ＫＮＯ无标度性，只是它们各自的参数不同．由已有的实验数据，计算出＝１８８ＧｅＶ处，碰撞的平均多重性〈ｎ〉＝４７．０及其荷电粒子的多重性的分布．可供实验检验．     

200A GeV S+Au反应中光子产生的低横动量增强

用建立在LUND弦模型特别是PYTHIA事件产生器基础上的描写极端相对论性核-核碰撞的强子和弦级联模型--JPCIAE研究了入射能量为200A GeV的S+Au中心碰撞中光子产生.模型同时考虑了部分子QCD散射过程、强子末态相互作用以及强子衰变等光子产生反应道并作了协调处理.JPCIAE模型计算结果很好再现了WA93实验数据所呈现的低横动量增强效应.     

ee0A GeV S+Au反应中光子产生的低横动量增强

用建立在LUND弦模型特别是PYTHIA事件产生器基础上的描写极端相对论性核一核碰撞的强子和弦级联模型—JPCIAE研究了入射能量为200A GeV的S+ Au中心碰撞中光子产生.模型同时考虑了部分子QCD散射过程、强子末态相互作用以及强子衰变等光子产生反应道并作了协调处理.JPCIAE模型计算结果很好再现了WA93实验数据所呈现的低横动量增强效应.     

核–核碰撞的独立源模型及中心快度区末态产生粒子横能量分布

将强子-核碰撞的独立源模型推广到核-核碰撞,给出了核-核碰撞末态产生粒子横能量分布方程,将其与CERN的NA35合作组得到的实验数据相比较,模型较好地解释了实验结果.     

膨胀的热夸克胶子物质的中等质量双轻子的增强

基于一个描述夸克胶子火柱演化的相对论流体力学模型,研究了夸克相、强子相互作用以及非热过程(DrellYan对、粲强子衰变)的中等质量双轻子的产生.发现由于相边对夸克胶子物质演化的影响和RHIC能量核碰撞产生的夸克胶子物质具有高的初始温度,夸克相对双轻子的贡献显著增强,比那些来自强子相互作用的贡献重要,甚至能与来自非热的贡献比较.表明中等质量双轻子的增强是一个在核碰撞中产生了夸克胶子物质的可能信号. 关键词： 夸克-胶子物质 双轻子增强 相对论流体力学模型     

相对论性重离子碰撞中负粒子的横动量和赝快度分布

基于三火球模型和强子共振态衰变图象,得到了相对论性重离子碰撞中负粒子的横动量和赝快度分布,并与200和60GeV/N ¹⁶O与An相互作用的有关实验结果作了比较.     

高能重离子碰撞实验中的软物理研究现状

高能重离子碰撞实验中的软物理研究能够帮助我们清楚认识系统的集体演化过程,并且有助于理解碰撞产生的热密系统的性质.本文介绍了高能重离子碰撞实验中软物理的研究现状及其新近取得的实验成果,包括七部分内容:1)高能重离子碰撞简介;2)碰撞几何方面的研究现状;3)粒子产生方面的研究现状;4)关联与起伏方面的研究现状;5)集体膨胀方面的研究现状;6)强子化方面的研究现状,7)LHC/ALICE实验上的软物理预期.最后,本文对高能重离子碰撞实验中的软物理研究现状进行总结.     

400GeV/c pp碰撞两粒子关联的角度依赖性

利用400GeV/c pp碰撞多重产生的实验数据计算了粒子-粒子关联(PPC)及其不对称性(PPCA)的角度依赖性.结果与L3的e⁺e^－数据有明显的差别,但与NA22强子碰撞的实验数据符合得很好;领头粒子对强子碰撞的PPCA分布有很大影响.通过计算两粒子方位角差的分布观察到了方位角关联.     

400GeV/c pp碰撞间歇指数的测量

利用CERNNA27合作组提供的LEBC泡室照片对400GeV/c pp碰撞产生的带电粒子赝快度分布进行了测量.计算了标度阶乘矩.得出间歇指数随矩阶数的增加而增加,随平均多重数的增加而变小;反常分形维数dq随q的增加而增加.这表明在强子-强子碰撞中多粒子产生具有自相似级联的性质.     

Erratic fluctuations in 14.5A GeV/c 28Si−AgBr Collisions

Analysis of multiparticle production data on 14.5A GeV/c ²⁸Si?AgBr collisions in terms of erraticity is carried out and the results are compared with those obtained from the Monte Carlo simulated data (using event generator HIJING). It is shown that like the multifractal spectrum through G _qmoments, erraticity spectrum may also be constructed from the observed power-law behaviour of the erraticity moments. Further, for examining the dominance of statistical fluctuations over the erraticity behaviour, correlation-free Monte Carlo events are simulated and analyzed. A comparison of the experimental and simulation results indicates that the fluctuations observed in the case of experimental data are not only because of the statistical reasons, but may have some dynamical origin.     

Multifractal statistics of multiparticle production at high energies

It is shown that high energy multiparticle production near the morphological phase transition from monofractality to multifractality is characterized by a multifractal Bernoulli distribution. Experimental data on hadron-hadron, hadron-nucleus and on heavy ions collisions are used to show an universal character of this distribution (and, consequently, of the morphological phase transition) in multiparticle production at high energies. Received: 23 July 1998 / Revised version: 25 November 1998     

The Excited Nucleon Model for High Energy N-N Collisions

Based on the quark model, we propose a new version for a detailed analysis of the energy exchange relation in multiparticle production of high energy hadron-hadron collisions. The multiplicities of various final state hadrons are calculated in the N-N collisions for a wide energy range (s=12 ～ 485 GeV²). The result predicts an energy dependence of various multiplicities and agrees with the experimental data quite well. It can be taken as a more reliable foundation to study the increase of the K/π ratio in pA and A-A collisions.     

The diffractive component of particle production in the dual multistring fragmentation model

The single diffractive component is introduced in the dual Monte Carlo chain decay model of soft particle production. The diffractively excited multiparticle states in this model arise from the fragmentation of two chains formed out of the valence quarks and antiquarks (or diquarks) of the diffractively excited hadron and a sea quark-antiquark pair of the Pomeron, considered to be a gluonic object. In this way the excited clusters behave in a way quite similar to multiparticle states formed in nondiffractive meson-hadron collisions. The calculated multiparticle states agree quite well with recent data from the UA4-SPS collider collaboration and with recent data on strange particle production in diffractive photon-proton collisions.     

Relating multihadron production in hadronic and nuclear collisions

The energy-dependence of charged particle mean multiplicity and pseudorapidity density at midrapidity measured in nucleus–nucleus and (anti)proton–proton collisions are studied in the entire available energy range. The study is performed using a model, which considers the multiparticle production process according to the dissipating energy of the participants and their types, namely a combination of the constituent quark picture together with Landau relativistic hydrodynamics. The model reveals interrelations between the variables under study measured in nucleus–nucleus and nucleon–nucleon collisions. Measurements in nuclear reactions are shown to be well reproduced by the measurements in pp/[`(p)]p{\bar{\mathrm{p}}}{\mathrm{p}} interactions and the corresponding fits are presented. Different observations in other types of collisions are discussed in the framework of the proposed model. Predictions are made for measurements at the forthcoming LHC energies.     

高能重离子碰撞多粒子产生的热力学模型研究

评述了高能重离子碰撞中多粒子产生的热力学模型,并根据该模型的最新发展,研究了有关高能核－核碰撞中簇射粒子的赝快度分布问题． The thermodynamic models for multiparticle production in high energy heavy ion collisions are reviewed.According to the recent developments of the thermodynamic models,the pseudorapidity distributions of shower particles produced in high energy nucleus nucleus collions are investigated.     

Self-affine analysis of multiparticle production in pp collisions at 400 GeV/c with continuously varying scale

A self-affine analysis of multiparticle production in pp collisions at 400 GeV/c was performed by using the method of continuously varying scale. Comparing with the results obtained from self-similar analysis, the self-affine analysis shows a better power-law behavior. The fractality in multiparticle production is self-affine rather than self-similar.     

Two-dimensional discrete wavelet analysis of multiparticle event topology in heavy ion collisions

The event-by-event analysis of multiparticle production in high energy hadron and nuclei collisions can be performed using the discrete wavelet transformation. The ring-like and jet-like structures in two-dimensional angular histograms are well extracted by wavelet analysis. For the first time the method is applied to the jet-like events. The jet positions are located quite well by the discrete wavelet transformation of angular particle distribution even in the presence of soft process background in nucleus-nucleus collisions at LHC energies.     

对高能碰撞末态粒子的阶乘矩拟合修正曲线的方贩

高能碰撞末态粒子在相空间的动力学分布存在着非均匀因素的影响,通过对这种非均匀因素影响的仔细研究,引入了修正系数,得到了拟合修正曲线的判据,给出了计算修正系数的方法.     

The dynamics of multiparticle collisions in motion of a granular material

We consider the complex problem of how to calculate particle motions taking into account multiparticle collisions. Multiparticle contacts occur when a particle collides with neighbouring particles, so that those contacts have a direct influence on each other. We will focus on the molecular dynamics method. Particularly, we will analyse what happens in cohesive materials during multiparticle contacts. We investigated the expression of repulsive force formulated under fractional calculus which is able to control dynamically the transfer and dissipation of energy in granular media. Such approach allows to perform simulations of arbitrary multiparticle collisions and also granular cohesion dynamics.