高能软、硬过程中非线性动力学起伏的对比研究

The experimental data of electron-positron collisions from L3 are analysed. The isotropic (self-similar) roperty of the multiparticle final ststes in electron-positron collisions is successfully observed in the first time, confirming the prediction of QCD. Consistent results are obtained by using the JETSET and HERWIG event generators to do Monte Carlo (MC) simulation. Comparing with our previous results on the anisotropic (self-affine) fractal in hadron-hadron collisions obtained under the support of NSFC projects, a qualitative difference between soft and hard processes is explored..Further on, using the 2-jet events in electron-positron collisions to study the fractal property inside jets, it is found that the system inside jets, mimic the final state system of hadron-hadron collisions, has anisotropic (self-affine) fractal property. This implies that the production of hard partons is a QCD hard process, while the fragmentation of the hard partons is semi-hard or soft process. The scale of the transition between hard and semi-hard processes (i.e. the production of "cone-like jets") is found to be 5~10 GeV. It is shown that this scale is consistent with the scale of experimentally observable jets..The angular method for the identification of quark and gluon jets is improved. A preliminary comparison of the fractal property inside quark and gluon jets is carried out. Using MC simulation, together with the NA22 data analysis, the influence of statistical fluctuations on erraticity is studied in some detail. It is shown that the erraticity phenomena proposed by R. Hwa and observed in some expriments are not connected with dynamics but are due to statistical fluctuations. It is proposed to utilize this property to construct a method for the observation of new physics in relativistic heavy ion collisions..The multi-fractal property in high energy electron-positron collisions is studied. It is found that the corresponding Levy index is less than 2, in consistence with the Levy stability condition. The corresponding multi-fractal spectrum is obtained..Besides, the non-thermal phase transition in multiparticle final states is studied using MC method..

通过蒙特卡洛模拟和分析L3电子正电子对撞实验数据，揭示软硬过程分形的定性差别。以此为指导，探索软过程自仿射分形的动力学根源，构造相应的蒙特卡洛产生器。为实验上确立的软过程的自仿射分形建立动力学基础。此外，还要结合NA22数据分形，研究统计起伏对混沌性质的影响；多粒子末态的非热相变与Levy稳定性等有关的高能非线性问题。