The study of Quark-Gluon-Plasma in ultrarelativistic nuclear Collisions

研究和取得的成果1.利用自行研制的160 GeV/nucleon附近pb-pb碰撞复合体的事件发生器，对160 GeV附近pb-pb碰撞复合体的热化过程进行了研究，并与中国原子能科学研究院（CIAE）合作进行了模拟和分析，主要结果如下：（1）热化过程在10^<@62>（-13）秒后发生; (2)获得的温度为80-110 MeV，持续时间约为3 × 10 ~（62）（1-13）秒。(3)达到的密度为10^<@62>（39）/cm^<@62>3.2。研究了粒子源尺寸与双粒子干涉测量时空参数之间的关系利用事件发生器对实际的时空扩展和干涉测量实验得到的时空参数进行了比较。主要结果是：（1）由于相对论性，整个时空的扩展不能用干涉测量实验观测到。(2)动量限制导致严重的差异。(3)这通常在纵向延伸中看到。这些结果已由中国原子能科学研究院的吕廷德先生在访问广岛时作了总结。无取向手性凝聚体的双粒子干涉理论研究了无取向手性凝聚体中的双粒子分布，这一理论已由T. DLu，Muroya，Miyamura和Hioki等人研究。结果是：（1）多dcc畴情况下的两π关联公式。(2)与π介子对不同，π介子对也有相关性。(3)Unlik π介子在动量小且相反的情况下是相关的。室谷先生与萨博华、郑延明访问中国原子能研究院，进一步拓展了本研究。有限密度下手征相变附近重子极化率的研究用Nambu-Jona-Lasinio模型计算了夸克-胶子等离子体手征相变附近重子极化率。在有限密度下发现了它的反常增强，它在早期宇宙高能核碰撞和核合成中的意义的研究仍在继续。

Research and obtalned results1. Study of temperature and density formed by the pb-pb collisions at energies around 160 GeV/nucleonThermalization of collision complex formed by pb-pb collisions at 160GeV is studied by an event generator developed in this collaboration.Simulations and analysis have been carried out in collaboration with CIAE.Main results are : (1) Thermalization undergoes after 10^<@62> (-13) second. (2) Achieved temperature is 80-110 MeV and its duration is about 3*10^<@62> (1-13) second. (3) Achieved density is 10^<@62> (39) /cm^<@62>3.2. Study of the relationsip between particle source size and space-time parameters obtained by two particle interferometryReal space-time extension and space-time parameters obtained by nterferometry experiment are compared by the use of event generator. Main results are : (1) Because of relativistic nature, whole space-time extension can not be observed by a interferometry : experiment. (2) Momentum restriction causes serious difference. (3) This is typically seen in longitudinal extension. These results have been summarized by T.D Lu (CIAE) in his visit at Hiroshima.3. Theory of two particle interferometry with disoriented chiral condensateTwo particle distribution from disoriented chiral condensate hnd been studied by T.D Lu, Muroya, Miyamura and Hioki. Results are : (1) Formula for two pion correlation in the case of many dcc domains. (2) Unlike pion pair has also correlation. (3) Unlik pions are correlated in the case of small and opposite momenta. This research has been extended by the visiting of Muroya at CIAE with B.H Sa and Y.M.Zheng.4. Study of baryonic susceptibility near the chiral phase transition at finite densityBaryonic susceptibility near chiral transition of quark-gluon plasma has calculated by Nambu-Jona-Lasinio model. At finite density, anomalous enhancement of it has been found. Study of implications of it in high energy nucleus collision and nucleosynthesis in early universe is now continuing.