Measurement of Born Cross Sections for $e^+e^-\to\Sigma^-\bar\Sigma^+$ at $\sqrt{s}=3.51-4.95$ GeV and Observation of $\psi(3770)\to\Sigma^-\bar\Sigma^+$

TL;DR

This paper reports the first measurements of the cross sections and form factors for $e^+e^- o ext{Sigma}^-ar{ ext{Sigma}}^+$ in the 3.51-4.95 GeV range and observes the decay $ ext{psi}(3770) o ext{Sigma}^-ar{ ext{Sigma}}^+$ with high significance.

Contribution

It provides the first measurement of these cross sections and observes a new decay mode of $ ext{psi}(3770)$, testing vector-meson dominance models.

Findings

First measurement of Born cross sections and form factors for the process.

Observation of $ ext{psi}(3770) o ext{Sigma}^-ar{ ext{Sigma}}^+$ decay.

Determination of cross section ratios for Sigma isospin states.

Abstract

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 44 fb$^{-1}$ collected with the BESIII detector at the BEPCII collider, we report the first measurement of Born cross sections and effective form factors for $e^+e^-\to\Sigma^-\bar\Sigma^+$ at centre-of-mass energies between 3.51 and 4.95 GeV. With a fit to the $\sqrt{s}$-dependent dressed cross sections, the decay $\psi(3770)\to\Sigma^-\bar\Sigma^+$ is observed for the first time with a significance of 5.5$\sigma$, including systematic uncertainties. Upper limits at the 90\% confidence level on the product of the branching fraction and the electronic partial width are provided for other possible charmonium(-like) states. The ratios of Born cross sections for the $\Sigma$ isospin-triplet states are determined and can be used to test the vector-meson-dominance model.