a Measurement of the u- and D-Type Hadronic Partial Widths of the Z Boson Using Long Range Charge Correlations.

The Standard Model of fundamental interactions proposed by Glashow, Weinberg, and Salam predicts different couplings of the different quark species to the Z ^0 depending on the third component of the weak isospin (I_3) of the species. Two of the five species to which the Z^0 is kinematically allowed to decay are denoted up and charm, have I_3={+{1over2} }, and are collectively referred to as u-type. The other three quark species are down, strange, and bottom, have I_3={-{1over2} }, and are said to be d-type. The u- and d -type species each have unique couplings to the Z ^0 that are predicted by the Standard Model. In this thesis I present a measurement of the u- and d-type hadronic branching fractions of the Z ^0. Long range charge correlations are shown to statistically distinguish u- from d-type events in Monte Carlo simulated decays of the Z^0. Monte Carlo estimates of charge correlations for u- and d-type events are then compared with those observed for multihadronic events in data taken by the OPAL experiment at CERN between 1992 and 1993 to extract their u- and d -type components. In support of the technique used, charge correlations are measured for subsets of the OPAL data in which the Z^0 has been tagged as decaying into a particular u- or d-type quark species. The measurement made here is then compared with the Standard Model prediction and with measurements made previously of the u- and d-type partial widths of the Z^0 using final state photons radiated from the primary quarks in the Z^0 decay.