Study ofY1*Resonant Amplitudes between 1660 and 2215 MeV in the ReactionK−N→Λπ

Abstract

We have extended the partial-wave analysis of the reaction $K^{-}N\to \Lambda \pi$ from our data in the energy region 1660 to 1900 MeV to the data at higher energies (1900 to 2215 MeV) from other experiments. This analysis has established the resonant nature of ${Y_1}^{*}\mathrm{}\left(1910\right)\mathrm{}$ and measured its spin and parity as $J^P={\frac{5}{2}}^{+}$. The earlier assignment $J^P={\frac{7}{2}}^{+}$ for ${Y_1}^{*}\mathrm{}\left(2030\right)\mathrm{}$ by Wohl et al. has been confirmed. The mass, width, and $\Lambda \pi$ branching ratio were measured as 1902±11 MeV, 52±25 MeV, and 0.08±0.04 for ${Y_1}^{*}\mathrm{}\left(1910\right)\mathrm{}$, and 2032±6 MeV, 160±16 MeV, and 0.41±0.03 for ${Y_1}^{*}\mathrm{}\left(2030\right)\mathrm{}$. In addition we found a suggestion for the existence of a $J^P={\frac{1}{2}}^{+}$ resonance at 1880 MeV with a width of 220 MeV.