Charmonium and exotics from Belle

TL;DR

This paper reviews recent Belle experiment results on charmonium and exotic states, including searches for X-like states, measurements of Y states, evidence for charged structures, and observations of X(3872), advancing understanding of charmonium spectroscopy.

Contribution

It provides new measurements and evidence for exotic charmonium-like states, including a charged structure and updated properties of Y states, using Belle data.

Findings

Evidence for a charged charmoniumlike structure at 4.05 GeV/c^2

Improved measurements of Y(4360) and Y(4660) properties

Observation of X(3872) in B decays

Abstract

The recent results on charmonium and charmoniumlike states from Belle experiment are reviewed. We summarise searches in $B$ decays for possible $X$-like states in final states containing $\eta_c$. The new measurement of $e^+e^-\to\pi^+\pi^-\psi(2S)$ improves the determination of the properties of $Y(4360)$ and $Y(4660)$. The fits including $Y(4260)$ are performed. Evidence for a charged charmoniumlike structure at $4.05~{\rm GeV}/c^2$ is observed in the $\pi^{\pm}\psi(2S)$ intermediate state in the $Y(4360)$ decays. Belle also updates the measurement on $e^+e^-\to KKJ/\psi$ via initial state radiation using the full data sample. Finally, Belle observed $X(3872)$ in $B\to K\pi + X(\to\pi^+\pi^-J/\psi)$.