Study of $e^+e^-\to\omega X(3872)$ and $\gamma X(3872)$ from 4.66 to 4.95 GeV

TL;DR

This study investigates the production of the X(3872) particle in electron-positron collisions at energies between 4.66 and 4.95 GeV, measuring branching ratios and cross section ratios, and setting upper limits on certain processes.

Contribution

First measurement of the ratio of radiative to hadronic decay branching fractions of X(3872) in e+e- collisions, and comparison of production cross sections with other charmonium-like states.

Findings

Measured the ratio R of X(3872) decay modes as 0.38±0.20 (stat.)±0.01 (syst.), with an upper limit of 0.83 at 90% CL.

Found the ratio of cross sections σ(ωX(3872))/σ(ωχc1) as 5.2±1.0 (stat.)±1.9 (syst.), and σ(ωX(3872))/σ(ωχc2) as 5.5±1.1 (stat.)±2.4 (syst.).

Set an upper limit of 0.23 at 90% CL on the ratio σ(γX(3872))/σ(ωX(3872)).

Abstract

Using data samples with an integrated luminosity of $4.5~\text{fb}^{-1}$ collected by the BESIII detector at center-of-mass energies ranging from 4.66 to 4.95 GeV, we study the processes of $e^+e^-\to\omega X(3872)$ and $e^+e^-\to\gamma X(3872)$. With the $e^+e^-\to\omega X(3872)$ process, the branching fraction ratio $R\equiv\frac{\mathcal{B}(X(3872)\to\gamma J/\psi)}{\mathcal{B}(X(3872)\to\pi^+\pi^- J/\psi)}$ is measured to be $0.38\pm0.20_\text{stat.}\pm0.01_\text{syst.}$ ($R< 0.83$ at 90\% confidence level). In addition, we measure the ratio of the average cross section of $e^+e^-\to\omega X(3872)$ to $e^+e^-\to\omega \chi_{c1}(\omega\chi_{c2})$ to be $\sigma_{\omega X(3872)}/\sigma_{\omega\chi_{c1}}~(\sigma_{\omega X(3872)}/\sigma_{\omega\chi_{c2}})=5.2\pm1.0_\text{stat.}\pm1.9_\text{syst.}~ (5.5\pm1.1_\text{stat.}\pm2.4_\text{syst.})$. Finally, we search for the process of $e^+e^-\to\gamma X(3872)$, and no obvious signal is observed. The upper limit on the ratio of the average cross section of $e^+e^-\to\gamma X(3872)$ to $e^+e^-\to\omega X(3872)$ is set as $\sigma_{\gamma X(3872)}/\sigma_{\omega X(3872)}<0.23$ at 90\% confidence level.