| This work includes an analysis of data from E852 experiment and concentrates on explaining meson production mechanisms in reactions with pion beam at 18 GeV/c2. An emphasis has been made on π −p → ηπ0 n, π−p → ηπ −p, π−p → η ′π−p reactions. Several experimental collaborations have studied similar reactions and have claimed the existence of, so called, exotic mesons. Some of this findings are however controversial and there are many puzzling questions concerning the nature of reported exotic signals.; The analysis of the E852 data presented in this work was accomplished by means of partial wave analysis (PWA) techniques and moment method. These two methods are complementary to each other and, as it was clearly demonstrated, they have to be used together to provide reliable interpretation of the data. The results obtained from PWA and moment method were compared with theoretical predictions based on well established meson phenomenology and very good agreement was achieved.; Based on the results of the presented analysis one can rule out the possibility of existence of low mass exotic meson reported by the E852 collaboration. Exotic meson with higher mass is less questionable although, as it was shown, the decay width of this candidate for exotic meson was overestimated. It was shown that signals previously interpreted as a signatures of exotic mesons are mainly due to re-scattering—a well understood phenomenon—and not due to the presence of an underlying exotic meson. Thus, whether the exotic mesons exist is still an open question.; The general conclusion from this work is, that in order to resolve a puzzle of existence of exotic mesons further experiments are needed where instead of pion beam one would use high energy real photons. |
