Inter-string Bose-Einstein Correlations in Hadronic Z Decays using the L3 Dectector at LEP

Abstract

Bose-Einstein Correlations (BEC) of identical bosons can be used for the femtoscopy of the production properties of bosons in high-energy particle collisions. The effect of BEC can be observed experimentally as an enhancement of the production of identical bosons with small four-momentum difference Q relative to a production that would occur in a world without Bose-Einstein statistics. In this thesis, inter-string BEC are studied in hadronic Z events at the center-of-mass energy of 91.2 GeV. Results are presented by comparing 1-string and 2-string systems: 2-jet with 3-jet events, quark with gluon jets, and pairs of identical pions originating from the same and from different sides of a gluon jet. Given the current statistical significance, our results support the presence of BEC in pairs of pions originating from two different sources when these two sources are overlapping, or, alternatively, the lack of any overlap at all