Signature of an $h_1$ state in the $J/\psi \to \eta h_1\to \eta K^{\ast 0}{\bar{K}}^{\ast 0}$ decay

Abstract

The BES data on the $J/\psi \to \eta K^{\ast 0}{\bar{K}}^{\ast 0}$ reaction show a clear enhancement in the $K^{\ast 0}{\bar{K}}^{\ast 0}$ mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of a L=0 resonance around threshold, which in this case would correspond to an $h_1$ state with quantum numbers $I^G(J^{PC})=0^{-}(1^{+-})$. A state around $1800\text{MeV}$ results from the interaction of the $K^{\ast }{\bar{K}}^{\ast }$ using the local hidden gauge approach. We show that the peak observed in $J/\psi \to \eta K^{\ast 0}{\bar{K}}^{\ast 0}$ naturally comes from the creation of this $h_1$ state with mass and width around $1830\text{MeV}$ and $110\text{MeV}$, respectively. A second analysis, model independent, corroborates the first result, confirming the relationship of the enhancement in the invariant mass spectrum with the $h_1$ resonance.