Studies of the fragmentation process in hadronic decays of Z⁰ boson

Sammanfattning: This thesis is based on the work that was done during 1992--1996 at the DELPHI detector at LEP. Its main parts are outlined below. The brief Introduction gives an overview of the science of Particle Physics, its development and contemporary status. The first chapter represents an introduction to the DELPHI detector at LEP, describing the main features of the LEP machine and the DELPHI detector as means to obtain an important information for the analysis. The second chapter is devoted to description of the development of one of the components of the DELPHI detector: the hadron calorimeter and its cathode readout system in particular. The third chapter describes the wide possibilities of QCD analysis using the information about hadronic decays of the Z boson produced in e+e- annihilation. The main goal of this work was to extract different components of the charged hadron cross section and to derive the gluon fragmentation function. In the fourth chapter results of the studies of two-particles correlations in hadronic Z decays are presented. The analysis of directional and transverse mass dependences of the Bose-Einstein correlations is performed.