Particle Interferometry in e+e- Annihilation

This thesis is the result of three years of work in Lund University, as a member of DELPHI group, at the Elementary Particle Physics Department. The work concerns the study of Bose-Einstein correlations in electronpositron collisions at LEP. Since the Jetset event generator and its implementation of the Bose-Einstein correlation eect, LUBOEI, is the most used tool in the particle physics community, a study of this simulator, its performances and some limitations of its applicability area are presented in the rst part of the thesis. In the second part, using DELPHI experiment data, the multidimensional analysis of the two-particle Bose-Einstein correlations is performed, testing the string model prediction that the transverse correlation length is considerably smaller than the longitudinal one. The dependence of the Bose-Einstein correlation function parameters on the average transverse mass of the boson pair is discussed for both Jetset hadronic events and DELPHI data.