Measurement of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}$ via initial state radiation at Belle

Measurement of $e^{+} e^{-} \to γ χ_{c J}$ via initial state radiation at Belle

Y. L. Han et al. (Belle Collaboration)

Phys. Rev. D 92, 012011 – Published 20 July 2015

Abstract

The process $e^{+} e^{-} \to γ χ_{c J}$ ( $J = 1$ , 2) is studied via initial state radiation using $980 {fb}^{- 1}$ of data at and around the $ϒ (n S)$ ( $n = 1$ , 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB asymmetric-energy $e^{+} e^{-}$ collider. No significant signal is observed except from $ψ (2 S)$ decays. Upper limits on the cross sections between $\sqrt{s} = 3.80$ and 5.56 GeV are determined at the 90% credibility level, which range from a few pb to a few tens of pb. We also set upper limits on the decay rate of the vector charmonium [ $ψ (4040$ ), $ψ (4160)$ , and $ψ (4415)$ ] and charmoniumlike [ $Y (4260)$ , $Y (4360)$ , and $Y (4660)$ ] states to $γ χ_{c J}$ .