Speaker
Mr
Martin Ripka
(JGU KPH)
Description
Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction $e^+e^-\to\gamma_{\mathrm{ISR}} X(3872)\to\gamma_{\mathrm{ISR}}\pi^+\pi^-J/\psi$ via the Initial State Radiation technique. The production of a resonance with quantum numbers $J^{PC}=1^{++}$ such as the $X(3872)$ via single photon $e^+e^-$ annihilation is forbidden, but is allowed by a next-to-leading order box diagram. We do not observe a significant signal of $X(3872)$, and therefore give an upper limit for the electronic width times the branching fraction $\Gamma_{ee}^{X(3872)}\mathcal{B}(X(3872)\to\pi^+\pi^-J/\psi)<0.13$ eV at the 90% confidence level. This measurement improves upon existing limits by a factor of 46. Using the same final state, we also measure the electronic width of the $\psi(3686)$ to be $\Gamma_{ee}^{\psi(3686)}=2213\pm 18_\mathrm{stat}\pm 99_\mathrm{sys}$ eV.
Primary author
Mr
Martin Ripka
(JGU KPH)
