Search for $ψ_0(4360)\rightarrow ηψ(2S)$ through the process $e^+e^- \rightarrow ηηψ(2S)$

TL;DR

This study searches for a $J^{PC}=0^{--}$ exotic state, $\psi_0(4360)$, predicted as a molecular bound system, in the process $e^+e^- \to \eta\psi_0(4360)$ with $\psi_0(4360)\to\eta\psi(2S)$ using BESIII data at $\sqrt{s}=4.84$, 4.92, 4.95$ GeV (0.9$\ \text{fb}^{-1}$). A partial reconstruction strategy is employed: one $\eta$ is reconstructed via $\gamma\gamma$, the other $\eta$ is inferred, and $\psi(2S)$ is reconstructed through $\pi^+\pi^-J/\psi$ with $J/\psi$ decays to $e^+e^-$ or $\mu^+\mu^-$. No significant signals are observed for either $\eta\eta\psi(2S)$ production or $\psi_0(4360)\to\eta\psi(2S)$ with an accompanying $\eta$, and 90% CL upper limits are set on $\sigma(e^+e^-\to\eta\eta\psi(2S))$ and on $\sigma(e^+e^-\to\eta\psi_0(4360))\cdot\mathcal{B}(\psi_0(4360)\to\eta\psi(2S))$. The results suggest tight production suppression near threshold and motivate future studies at higher energy and luminosity, e.g., with the BEPCII-U upgrade up to $\sqrt{s}\approx 5.6$ GeV.

Abstract

Using data samples corresponding to an integrated luminosity of 0.9~fb$^{-1}$ collected with the BESIII detector operating at the BEPCII storage ring at the center-of-mass energies of 4.84, 4.92, and 4.95~GeV, we search for the exotic charmonium-like state with quantum numbers $J^{PC}=0^{--}$, $ψ_0(4360)$, in the process $e^+e^-\rightarrowηψ_0(4360)$ with $ψ_0(4360)\rightarrowηψ(2S)$. No significant signal of the $ψ_0(4360)$ resonance state is observed. Upper limits on $σ(e^+e^-\rightarrowηψ_0(4360))\cdot {B}(ψ_0(4360)\rightarrowηψ(2S))$ and $σ(e^+e^-\rightarrowηηψ(2S))$ at the 90\% confidence level are determined for each energy point.

Figures (2)

• Figure 1: Distributions of $M(\eta_2)$ and $M(\pi^{+}\pi^{-}J/\psi)$ combined from all c.m. energies. The black dots with error bars denote the real data, the green dashed histograms denote the inclusive MC simulation, and the red histograms correspond to the signal MC simulation of $e^+e^-\rightarrow\eta\eta\psi(2S)$. The blue vertical lines indicate the signal regions of $\eta_2$ and $\psi(2S)$.
• Figure 2: Distributions of $M(\pi^{+}\pi^{-}J/\psi)$ and $M(\eta_h\psi(2S))$ at the c.m. energies of 4.92 and 4.95 GeV. The black dots with error bars denote data, the green dashed histograms denote the inclusive MC and the red histograms denote the signal MC simulation of $e^+e^-\rightarrow\eta\psi_0(4360)$. The blue solid lines mark the signal regions of $\psi(2S)$ and $\psi_0(4360)$.