Search for Charmonium(-like) states decaying into the $Ω^-\barΩ^+$ final states

Abstract

Recently, the BESIII experiment performed a measurement of the energy-dependent Born cross section and the effective form factor for the $e^+e^-\toΩ^-\barΩ^+$ reaction at center-of-mass energies ranging from 3.4 to 4.7 GeV. A fit to the energy dependence of the dressed cross section is performed. With the assumption of a charmonium (like) resonance [i.e., $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, or $Y(4660)$] plus a power-law function, the fit is applied to the data from the recent BESIII measurement, which was additionally combined with previous CLEO-c measurement data. No significance is found. The products of the branching fraction and the two electronic partial widths for the assumed charmonium(-like) states decaying into the $Ω^-\barΩ^+$ final states are also provided. In addition, by taking the world average values of the electronic branching fraction, the branching fractions for $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $ψ(4415)$ decaying into $Ω^-\barΩ^+$ final states at the 90\% confidence level are determined for the first time. These are found to be at least an order of magnitude larger than expected from predictions using a scaling based on the observed electronic widths.

Figures (4)

• Figure 1: The dressed cross section ($\sigma^{dressed}$) and ${\Omega}^{-}$ effective form factor ($G_{eff}(s)$) for the $e^+e^-\to \Omega^-\bar{\Omega}^+$ reaction as a function of the c.m. energy from BESIII bib0042bib0061 and CLEO-c experiments bib0057. The error bars represent the statistical and systematic uncertainties summed in quadrature.
• Figure 2: Fit to the dressed cross section at the c.m. energies from 3.4 to 4.7 GeV with the assumptions of a PL function only (upper left) and a PL function plus a charmonium(-like) resonance [i.e., $\psi(3770)$, $\psi(4040)$, $\psi(4160)$, $Y(4230)$, $Y(4360)$, $\psi(4415)$, or $Y(4660)$]. Dots with error bars are the dressed cross sections, and the solid lines show the fit results. The error bars represent the statistical and systematic uncertainties summed in quadrature.
• Figure 3: The contour of $\Gamma_{ee}\mathcal{B}$ and $\phi$ on the distribution of $\chi^2$ values for $\psi(3770)$, $\psi(4040)$, $\psi(4160)$, $Y(4230)$, $Y(4360)$, $\psi(4415)$, or $Y(4660)$ decaying into the $\Omega^-\bar{\Omega}^+$ final states. The cyan points represent the solutions from the best fit.
• Figure 4: Fit to the dressed cross section at the c.m. energies from 3.4 to 4.7 GeV with the assumption of a continuum contribution (PL) plus seven charmonium(-like) resonances [i.e., $\psi(3770)$, $\psi(4040)$, $\psi(4160)$, $Y(4230)$, $Y(4360)$, $\psi(4415)$, or $Y(4660)$]. Dots with error bars are the dressed cross sections, the solid lines show the fit results, and different dashed lines represent the continuum contribution and different resonance states.