Reaction K−p→K−pπ+π− at 2.0 GeVc

Abstract

An analysis of the reaction $K^{-}p\to K^{-}p{\pi }^{+}{\pi }^{-}$ at 2.0-$\frac{\mathrm{GeV}}{c}$ incident momentum is presented. The total cross section for the reaction is 627±20 $\mu b$, based on 4519 events. The reaction is dominated by resonance production through several channels which overlap kinematically but do not appear to interferesubstantially. A maximum-likelihood procedure was used to determine the production fractions, which for the major channels are 0.44±0.02 for $N^{*++}\mathrm{}\left(1236\right)\mathrm{}$, 0.145±0.02 for $Y^{*0\mathrm{}}\mathrm{}\left(1520\right)\mathrm{}$, 0.10±0.03 for $N^{*+}\mathrm{}\left(1688\right)\mathrm{}$, and 0.20±0.02 for simultaneous ${\overline{K}}^{*0\mathrm{}}{N}^{*0\mathrm{}}$. Evidence is presented for the production of $Y^{*+}\mathrm{}\left(1765\right)\mathrm{}$ and its decay into $Y^{*0\mathrm{}}\mathrm{}\left(1520\right)\mathrm{}$ as well as for production of $Y^{*+}\mathrm{}\left(1660\right)\mathrm{}$ with decay into $K^{-}p{\pi }^{+}$. A four-standard-deviation enhancement is present at a $K^{-}{\pi }^{+}$ invariant mass of 690 MeV. Angular correlation data are presented for the $N^{*++}{K}^{-}{\pi }^{-}$, $Y^{*0\mathrm{}}{\pi }^{+}{\pi }^{-}$, and ${\overline{K}}^{*0\mathrm{}}{N}^{*0\mathrm{}}$ reaction channels. However, the difficulty of separating the various channels prevents a detailed study of the reaction dynamics.