Higgs boson search with discriminant analysis methods

We have investigated two different variations of discriminant analysis to detect the signal of a Higgs boson produced in association with neutrinos in e+e− collisions at 183 GeV. In one case eleven event variables were used together in two steps of an iterated discriminant analysis, while in the other case (structured discriminant analysis) groups of variables were treated independently. Background rejection factors of about 16 000 for the most important background were obtained with an efficiency of 32% for events with a Higgs boson mass of 85 GeV/c2. The optimization and performance are described for the two variations, and the final results of the iterated discriminant analysis used in the DELPHI experiment are given.