Speaker
Xiaobin Ji
(Institute of High Energy Physics, CAS, Beijing)
Description
With 58M $J/\psi$ events at BESII, an anomalous enhancement, $X(1860)$, near the mass threshold in the $p \bar p$ invariant mass spectrum from $J/\psi \to \gamma p \bar p$ decays was reported. And a resonance named $X(1835$ is also observed in $\eta' \pi^+\pi^-$ invariant mass spectrum from $J/\psi \to \gamma \eta' \pi^+\pi^-$. Whether $X(1860)$ and $X(1835)$
are the same resonance or not needs further confirmation.
With 100M $\psi(2S)$ events collected at BESIII, the $p \bar
p$ threshold enhancement $X(1860)$ is confirmed in the decays of
$\psi(2S) \to \pi^+ \pi^- J/\psi, J/\psi \to \gamma p \bar p$. The
mass and width of $X(1860)$ are consistent with those from BESII
data. It is also confirmed in $J/\psi \to \gamma p \bar p$ with 200M
$J/\psi$ data sample.
The decays of $J/\psi \to \gamma \eta' \pi^+\pi^-$ are examined too.
The resonance $X(1835)$
is confirmed with a much higher statistical significance. We also study
the isospin breaking process $J/\psi \to \phi f_0(980)$ for the
study of $a_0(980)$ and $f_0(980)$ mixing. The preliminary results are presented.
Primary author
Xiaobin Ji
(Institute of High Energy Physics, CAS, Beijing)
