Amplitude analysis of reactionsπ−p→ηπ−pand

Abstract

Recently several experimental groups analysed data on π − p → ηπ − p and π − p → ηπ 0 n reactions with exotic 1 −+ P -wave and found a conflicting evidence for an exotic meson I = 11 −+ (1405). High statistics data on these reactions are presently analysed by BNL E852 Collaboration. All these analyses are based on the crucial assumption that the production amplitudes do not depend on nucleon spin. This assumption is in sharp conflict with the results of measurements of π − p → π − π + n, π + n → π + π − p and K + n → K + π − p on polarized targets at CERN which find a strong dependence of production amplitudes on nucleon spin. To ascertain the existence of exotic meson