Observation of a New Excited $\Sigma$ State in $\psi(3686)\to\bar{p}K^+\Sigma^0+c.c.$

TL;DR

This study reports the discovery of a new excited $\Sigma$ baryon state in $\psi(3686)$ decays, with precise measurements of its properties and implications for baryon spectroscopy.

Contribution

The paper presents the first observation of a new excited $\Sigma$ state with detailed measurements of its mass, width, and spin-parity, using a large data sample and partial-wave analysis.

Findings

Discovery of a new $\Sigma$ baryon state with 11.9$\sigma$ significance.

Measured mass and width of the new state as 2334.7 MeV/c$^2$ and 206.3 MeV.

Determined branching fractions for $\psi(3686)$ decays involving the new state.

Abstract

Using a data sample of $(2712.4\pm14.3)\times10^6\ \psi(3686)$ events collected with the BESIII detector, a partial-wave analysis of $\psi(3686)\to\bar{p}K^+\Sigma^0+c.c.$ is performed. A new excited $\Sigma$ baryon state is observed with a statistical significance of $11.9\sigma$, and the mass and width are measured as $(2334.7\pm7.9\pm16.0)\;\mathrm{MeV}/c^2$ and $(206.3\pm9.5\pm18.4)\;\mathrm{MeV}$, respectively. The spin-parity of the new state is favored to be $3/2^-$, and the branching fraction of $\psi(3686)\to\bar{\Sigma}(2330)^0\Sigma^0+c.c.$ is determined to be $(4.47\pm0.58\pm1.52)\times10^{-6}$. In addition, the branching fraction of $\psi(3686)\to\bar{p}K^+\Sigma^0+c.c.$ is determined to be either $(2.44\pm0.20\pm0.08)\times10^{-5}$ or $(1.73\pm0.29\pm0.06)\times10^{-5}$ by considering two solutions. The first uncertainties are statistical and the second systematic.