The Study Of Events Fluctuations In High Energy Collisions

In this thesis the erraticity of event factorial moments and of event rapidity gaps have been studied.The phenomena that the fluctuations of event factorial moments increase with decreasing phase space, called erraticity. It has been demonstrated that the behavior of erraticity is dominated by statistical fluctuations when the multiplicity is low. To study the behavior of erraticity in high energy nucleus-nucleus collision, two different Monte Carlo generators FRITIOF and VENUS are used to simulate different nucleus-nucleus collision samples. The behavior of erraticity at different collision conditions and related constrain are presented. We find that the erraticity of event factorial moments is still dominated by the statistical fluctuations though the multiplicity is already several hundreds and several thousands. This result does not depend on the models. Nor does it depend on the collision conditions, e.g., the collision energy, the mass of colliding nuclei, and the physics constrains, e.g., the cut of phase space, particle type, average multiparticle, etc. No dynamical fluctuation has been observed through event factorial moments analysis. Nowever this may imply that the errraticity method is sensitive to the appearance of novel physics in the central collosion of heavy nuclei. That's to say, the observed erraticity will deviate from that of pure statistical fluctuations only if the events of the studied sample are coming from some new kind of physical processes.In the investigation of the event rapidity gaps fluctuations, the stability of two moments Sq and E, with event number, which have been proposed by Hwaet al, are studied. In experimentally reachable number of events if multiplicity is low, the measure of Sq is stable, but the measure of Eg is rather unstable. The stability of Sg get well improved by slightly increasing multiplicity. Then for the experimental data produced by r+p and K+p collisions at 250 GeV/c, the four moments which describe event rapidity gaps fluctuations, are calculated. It is found that Sq, Eq and Eq all deviate significantly from 1. This seems to indicate that they all can show dynamical fluctuation in multiplicity production. As to Sq, it almost equals to 1. This imply that it is not a good measurment of event rapidity gaps fluctuations. The ]nSq versus hi q has a quite linear behavior. But both the hi Eq and hi Sq versus q has only approximate linear behavior, and the error bars are big. The shortage of event number in experimental sample cause the unstable. Following that, we research the relation between the measure for pure statistical samples and that of corresponding data samples, and find that the former is smaller than the later. This is understandable since the rapidity distribution of pure statistical sample is more uniform than that of corresponding data sample. The same analysis are performed at PYTHIA Monte Carlo sample. The experimental results are compared with that of PYTHIA and ECOMB. All the simulative results underestimate that of experimental data. This seems that the erraticity analysis of rapidity gaps can be used to check models in multiparticle production.