The Features Of The Two-pion Correlation Functions For Granular And Partially Coherent Sources

The major goal of high energy heavy ion collision is to investigate nuclear matter properties under extreme conditions and detect quark-gluon plasma (QGP). Intensity interferometry technique is a developed means for the study of high-energy heavy-ion collision physics, is also an important tool to study the space-time feature and coherence of particle-emitting source and an effective method to examine the quantum chromodynamics(QCD) phase transition. Quark-gluon plasmaFirst, related important points of intensity interferometry in this paper are generalized and the research objectives and research contents are given in introduction of this thesis. Then the present researches are addressed in the following chapters systemically. The main researches and innovations of this thesis are divided into three sections: QGP signals in single-event pion interferometry for granular sources of quark-gluonplasma droplets; asymmetry analysis of emission function for partially coherent sources; the relation of back-to-back correlation of particle-antiparticle and mass shifting of quasi-particle in sources.Particle-emitting source produced heavy ion collision may have granular structure under RHIC energy ( s NN?200 GeV) and the"HBT puzzle"of RHIC is explained by granular sources model. To avoid statistical fluctuation, correlation function is studied by mixing event methods on average event sample for granular sources. The obtained functions can not reflect granular structure of source. We try to outline a new method to study the granular sources using fluctuations of the single event correlation function relative to its corresponding mixed-event correlation function. The Monte-Carlo simulation indicates that there are fluctuations for the single-event correlation function relative to the mixed-event correlation function, and the fluctuations distribution width increase as the number of droplets decreases. We define the distribution function of fluctuations to quantitatively study fluctuations. It can be seen that the width of the distribution for the granular source increases with the number of droplets decreases.Due to important significance of coherence of source on obtaining correlation function proper form and understanding particle production mechanism, we focus on the correlation function of partially coherent identical particle-emitting sources within quantum statistical formalisms, where the sources are treated as classical currents. There is a phase (?) in the coherent term of correlation function and ? is sensitive to asymmetry of emission function by studying expression of phase. In Glauber rescattering theory sources are opaque due to particles emitting from a surface layer with a depth of order of the mean free path. Hydrodynamical models assume that particle-emitting sources expand during its evolution. Opaque and expanding effects of sources make particle-emitting position tend to the surface of sources. These two physical effects makes emission function asymmetry and phase nonzero, and influence correlation function through phase.The effect of phase on correlation function is investigated on the influence of asymmetry of particle-emitting sources and the correlation function of partially coherent sources is simulated by certain model. The correlation function for chaotic sources is expressed by emission function and the algorithm of calculating chaotic sources is generalized to be applicable to partially coherent sources. The simulation result shows that phase has increasely influences on correlation function because of opaque and expanding effects along with the reduction of chaoticity parameter. The Gaussian parameterization forms fitting of two-pion correlation functions for partially coherent sources indicate that the opaque and expansion effects lead to a smaller interferometry radius Ro ut and a larger chaoticity parameterλ.The particle-antiparticle correlation except identical particle might appear in particle-emitting sources forming in high energy nuclear-nuclear collision. If particle production process is described by density matrix in quantum statistics and the invariant single-particle and two-particle momentum distribution is expressed by the creation and annihilation operator, there is back-to-back correlation between particle and antiparticle. To analyze the dynamical mechanism of particle-antiparticle correlation we proceed to study the energy of particle field and free particle is related to quasi-particle produced by hadronization of QGP phase by Boguolubov transformation, back-to-back correlation is due to mass shifting of quasi-particle caused by interactions in a dense medium. Mass shifting has effects on HBT correlation of identical particles.