A STUDY OF MULTIPARTICLE PRODUCTION IN HIGH ENERGY PROCESSES

Abstract

In investigating the effect of the coulomb interaction on the nuclear energy spectra, the isobaric analog spin is introduced as a plausible candidate to replace the isospin symmetry. The complete isomorphism of the isospin and analog spin representations is developed by using the group theoretical approach. The Hamiltonian in the analog spin representations is then set up and the relationships between the matrix elements in the two representations are established. Algebraic technique is developed to evaluate the analog-spin external partial width ar1d to minimize the analog spin admixings. Based on the analog spin symmetry the low lying spectra of various nuclei in the ds shells are projected by the standard spectral distribution method. Comparisons are made with the experimental results and with the calculations based on the isospin symmetry. In general, the spectra of the even-even nuclei are not much different in the two representations; however significant improvement (in comparison with empirical spectra) has been achieved for odd-A nuclei in the analog spin representation. This thesis is divided into two parts, part I reviews the two extreme pictures in multiparticles productions, i. e. the multiperipheral picture which assumed the secondary particles come off a multiperipheral chain, and the diffractive fragmentation picture which assumed the secondary particles come from the fragments of projectile (or target). There are some basical shortcomings in this two pictures. Hence the two-component picture was proposed intently to overcome the weaknesses of the above two pictures. In higher energy range, a dip in the multiparticle distribution, which was not observed experimentally, appears in the prediction of two-component model. It lead us to propose the three-fireball model in part II. The model assumed that pionization and fragmentation occur simultaneously in a interaxtion. The model was applied .to account for the Wroblewski's linear Dispersion rule, charge transfer in 205 Oev/c and the azimuthal correlations. The fits are good.