Observation of a New Excited $\hat{I}\pounds$ State in $\ddot{I}ˆ(3686)\to \bar{p}{K}^{+}\hat{I}{\pounds }^0+c.c.$

Abstract

Using a data sample of $(2712.4\pm 14.3)\times 10^6\ddot{I}ˆ(3686)$ events collected with the BESIII detector, a partial-wave analysis of $\ddot{I}ˆ(3686)\to \bar{p}{K}^{+}\hat{I}{\pounds }^0+c.c.$ is performed. A new excited $\hat{I}\pounds$ baryon state is observed with a statistical significance of $11.9\ddot{I}ƒ$, and the mass and width are measured as $(2334.7\pm 7.9\pm 16.0)\mathrm{MeV}/c^2$ and $(206.3\pm 9.5\pm 18.4)\mathrm{MeV}$, respectively. The spin-parity of the new state is favored to be $3/2^{-}$, and the branching fraction of $\ddot{I}ˆ(3686)\to \bar{\hat{I}}\pounds (2330{)}^0\hat{I}{\pounds }^0+c.c.$ is determined to be $(4.47\pm 0.58\pm 1.52)\times 10^{-6}$. In addition, the branching fraction of $\ddot{I}ˆ(3686)\to \bar{p}{K}^{+}\hat{I}{\pounds }^0+c.c.$ is determined to be either $(2.44\pm 0.20\pm 0.08)\times 10^{-5}$ or $(1.73\pm 0.29\pm 0.06)\times 10^{-5}$ by considering two solutions. The first uncertainties are statistical and the second systematic.

10 pages, 3 figures, etc