A ‘Ranking’ method for neutral pion selection in high multiplicity hadronic events

The selection of neutral pions with a high purity while maintaining also a high efficiency can be important in the formation of statistically significant mass spectra in the reconstruction of short-lived particles such as the omega meson (ω→π+π−π0). In this study a Ranking method, where pions are ranked according to a pion estimator, is described and detailed results from a Monte-Carlo study are presented. The results show that the Ranking method, when applied to high multiplicity events, yields significant improvements in the purity of selected pion candidates and facilitates the relaxation of standard cuts thereby avoiding some systematic uncertainties.