The π π Ʌ channel from k(^-)p reactions in the Ʌ (1690) region

Abstract

This work represents a study of the Ʌ π π final state of KN interactions between 0.620 and 0.870 GeV/c incident laboratory momentum. Data obtained from a Hydrogen bubble chamber exposure has been used to obtain channel cross-sections for the reaction k (^-) p → Ʌπ(^+)π(^-). Study of the Ʌπ(^+)π(^-) Dalitz plot reveals that in addition to E(^+) (1385) and E(^-) (1385) isobar production, final state π π S-wave interaction (‘e’) is present. Assuming a model of incoherent addition, quasi-two body descriptions for each of the π(^+) E(^-) (1385), π(^-)E(^+) (1385) and ‘E’ Ʌ channels are extracted. Subsequent consideration of the πE(1385) quasi two-body channels reveals evidence for strong Δ(1690) formation. Combining the newly obtained data with that previously published for the πE(1385) channels, an energy dependant partial ave analysis is performed. Resonant amplitudes of the SO1(1670), D13(1670), D13(1678) and DO3(1690) states are determined. Consideration of the DD03 and DS03 partial wave amplitudes for the DO3(1690) state, indicates substantial Ʌ(^4)8(_3) – Ʌ(^2)8(_3) mixing within SU(^6) w O O (3). In addition, a comparison is given between the amplitudes Y(^*) states observed in the partial wave analysis and those predicted by the Isgur-Karl Model.