| Explore the deepest level of the microstructure inside matter is one of the most important tasks in physics research. When scientists found that the atom taken as the elementary particle before is composed of more fundamental particles which are electron, proton, neutron. the elementary particle was redefined. Then the Subsequent experimental results began to overturn previous definition again, which proved that the previous defined elementary particle has deeper internal structure. At present, scientists have studied and explored the internal structure of matter from the level of quarks and gluons. Therefore, with the improvement of theoretical knowledge and technological advances, understanding of the elementary particle will be more rich and comprehensive.Elementary particles have complex interactions, contain the following four kinds: gravitational interaction, electromagnetic interaction, the weak interaction and the strong interaction. There is the strong interaction between quarks, this interaction conducted by massless gluons. So far, Quantum chromo-dynamics(QCD) is the most successful theory which describes strong interactions between quarks. In this theory, there are two very important characteristics:asymptotic freedom and color confinement (or quark confinement). Because of the color confinement (or quark confinement), we can not directly observe individual quark or gluon except the final state of hadrons formed by quarks and gluons in the laboratory. However, scientists can indirectly get the feature of the strong interaction by analyzing hadronization product formed by quarks and gluons. In the experiment, people found the theoretically predicted Jet including events of two-jet and three-jet, which strongly proved the existence of gluons predicted by parton models. Jets is considered as a powerful tool for studying the structure of high-temperature and high-density matter as well as characters of new form of matter in relativistic heavy ion collisions.To begin with, this paper introduces some important theoretical concepts and models in heavy ion collisions. Such as:multiphase transport (AMPT) model, PACIAE model and PYTHIA model. Then the article is divided into the following sections to introduce our research work:The first part mainly introduces the identification and characteristic of mini-jet in heavy ion collisions. In the second part, we specifically analyze the distribution features of the internal particles in mini-jet. In the third part, we mainly introduce the production of anti-light nuclei in relativistic heavy ion Au+Au collision. Including the calculation of anti-light nucleus’ yields and their feather’s analysis.In the first part, we start with the introduction of concept of cone in mini-jet. Then, based on "the method of defined cone" proposed by Liu Ming, we put forward a new set of method of identification of mini-jet in relativistic heavy ion collisions. After producing Au+Au collisions data sample events at200GeV center energy by the multiphase transport model (AMPT), we use the new method to pick out the mini-jet from the data sample events. What’s more, After analyzing the dependence of selected mini-jets numbers on various parameters (such as cut parameter, transverse momentum parameter), we find that:this method exist strong parameters dependence, however, this effect will become weaker when the value of parameters exceeds a certain range. Also, we analyze the dependence of mini-jets on energy parameter and collision parameter, then we known the number of mini-jets raises with the energy parameter increasing, reduces by the increasing of collision parameter.In the second part, we further study the some distributions of particles inside mini-jets, including the distributions of rapidity, transverse momentum and cone angular. According to this study, it is easy to know that most of the particles inside mini-jet are distributed in the center rapidity range (the value close to zero), so there are less particles in greater value of rapidity. In addition, the rapidity distribution of all particles is substantially similar, and nothing to do with whether particles are charged. What’s more, the distribution of transverse momentum with all particles inside mini-jet also has similar situation regardless of whether they carry charge. In the end of this section, after analyzing the dependence of different distributions inside mini-jet on energy parameter and collision parameter, we notice that:with the increasing of energy parameter, cone angular distribution sharply reduce and its displacement gradually move to the right, the range of rapidity distribution become widen and its centre has a invariant flat. However the distribution of cone angular and rapidity has nothing to do with collision parameter, even the distribution of transverse momentum can not be effected by both of the two parameters. In the end of the part, after briefly introducing the dynamically constrained coalescence model used in creating (anti-light) light nuclei and hyper (anti-hyper) nuclei, we calculated their yields, ratios as well as the transverse momentum distributions. After comparing this data with the STAR lab data, we find our results maintain a high degree of consistency with these data. So we come to a conclusion that the dynamically constrained coalescence model can well describe the productions of (anti-light) light nuclei and hyper (anti-hyper) nuclei in relativistic heavy ion collisions. |
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