Observation of resonant contribution to the $e^+e^-\to \Omega^{-}\bar{\Omega}^{+}$ around 4.2 GeV and evidence of $\psi(3770)\to \Omega^{-}\bar{\Omega}^{+}$

TL;DR

This study observes a resonant structure around 4.2 GeV in the process $e^+e^- o \Omega^{-}ar{\Omega}^{+}$, providing evidence for $\psi(3770)$ decay to this final state and measuring its branching fraction.

Contribution

First measurement of energy-dependent cross sections for $e^+e^- o \Omega^{-}ar{\Omega}^{+}$ including resonant contributions, and first evidence of $\\psi(3770)$ decay to this baryon pair.

Findings

Resonant structure around 4.2 GeV with >10σ significance.

Evidence for $\\psi(3770) o \\Omega^- \\bar{\\Omega}^+$ with 4.4σ significance.

Branching fraction of $\\psi(3770)$ decay measured as $(4.0\\pm1.0\pm0.6) \\times 10^{-5}$.

Abstract

Using $e^+e^-$ collision data corresponding to a total integrated luminosity of 22.7 fb$^{-1}$, collected at center-of-mass energies between 3.7 and 4.7 GeV with the BESIII detector, we present a measurement of energy-dependent cross sections and effective form factors for the process of $e^+e^-\to \Omega^{-}\bar{\Omega}^+$. By conducting a fit to the cross sections of $e^+e^-\to \Omega^{-}\bar{\Omega}^+$ considering the continuum and resonant contributions, a clear resonant structure in the spectrum around 4.2 GeV is observed for the first time with a statistical significance exceeding 10$\sigma$, and it can be well described with the line shape of the $Y(4230)$ and $Y(4320)$ observed in $e^+e^-\to \pi^{+}\pi^{-}J/\psi$. Evidence for the decay $\psi(3770) \to \Omega^-\bar{\Omega}^{+}$ is observed with a statistical significance of 4.4$\sigma$ by analyzing the measured cross sections together with earlier BESIII results, and the branching fraction is firstly measured to be $(4.0\pm1.0\pm0.6)$ $\times$ $10^{-5}$, where the first uncertainty is statistical and the second is systematic.