Study of the near-threshold $\omega\phi$ mass enhancement in doubly OZI suppressed $J/\psi \to \gamma\omega\phi$ decays

TL;DR

This study reports the observation of a near-threshold enhancement in the $ ext{ }$ mass spectrum in $J/ o\u03b3 ext{ extasciitilde}$ decays, confirming the existence and properties of the X(1810) resonance with detailed analysis.

Contribution

The paper provides the first detailed partial wave analysis confirming the quantum numbers and properties of the X(1810) resonance in doubly OZI suppressed $J/$ decays.

Findings

Observation of a significant near-threshold enhancement in $ ext{ extasciitilde}$ mass spectrum.

Determination of the X(1810) resonance's mass, width, and quantum numbers.

Measurement of the product branching fraction for $J/ o\u03b3X(1810)$ and $X(1810) o ext{ extasciitilde}$.

Abstract

A 2.25$\times10^8$ $\jpsi$ event sample accumulated with the BESIII detector is used to study the doubly OZI suppressed decay modes $\jpsi\to\gamma\of$, $\omega\to\ppp$, $\phi\to\kk$. A strong deviation ($>$ 30$\sigma$) from three-body $\jpsi\to\gamma\omega\phi$ phase space is observed near the $\omega\phi$ mass threshold that is consistent with a previous observation reported by the BESII experiment. A partial wave analysis with a tensor covariant amplitude that assumes that the enhancement is due to the presence of a resonance, the X(1810), is performed, and confirms that the spin-parity of the X(1810) is $0^{++}$. The mass and width of the X(1810) are determined to be $M=1795\pm7$(stat)$^{+13}_{-5}$(syst)$\pm$19(mod) MeV/$c^2$ and $\Gamma=95\pm10$(stat)$^{+21}_{-34}$(syst)$\pm$75(mod) MeV/$c^2$, respectively, and the product branching fraction is measured to be ${\cal B}(\jpsi\to\gamma X(1810))\times{\cal B}(X(1810)\to\of)=(2.00\pm0.08$(stat)$^{+0.45}_{-1.00}$(syst)$\pm$1.30(mod))$\times10^{-4}$. %where the first error is the statistical error and the second the systematical error. These results are consistent within errors with those of the BESII experiment.