Partial Wave Analysis of $J/\psi\rightarrow \gamma \gamma \phi$

TL;DR

This paper performs a detailed partial-wave analysis of the decay $J/9$ to identify intermediate resonances, measure their properties, and explore implications for meson spectroscopy and charmonium states using a large data sample.

Contribution

It provides the first detailed partial-wave analysis of $J/9$ decaying to $99999$, identifying multiple resonances and precisely measuring their parameters, including $9(1405)$ and $X(1835)$.

Findings

Resonances including $f_{1}(1285)$, $9(1405)$, $f_{1}(1420)$, $f_{1}(1510)$, $f_{2}(1525)$, $X(1835)$, $f_{2}(1950)$, $f_{2}(2010)$, $f_{0}(2200)$, and $9$ detected with >5$c$ significance.

Precise determination of resonance parameters for $9(1405)$ and $X(1835)$.

Observation of $9 ightarrow99 ightarrow999$ supports their interpretation as excited states of $9^{c}$.

Abstract

Using a sample of $(10087\pm44)\times10^{6}$ $J/\psi$ events collected by the BESIII detector at the BEPCII collider, a partial-wave analysis of the decay $\gamma\gamma\phi$ is performed to investigate the intermediate resonances in $J/\psi\rightarrow\gamma R, R\ar\gamma\phi$. Resonances including $f_{1}(1285)$, $\eta(1405)$, $f_{1}(1420)$, $f_{1}(1510)$, $f_{2}(1525)$, $X(1835)$, $f_{2}(1950)$, $f_{2}(2010)$, $f_{0}(2200)$ and $\eta_{c}$ have been detected with statistical significance greater than 5$\sigma$. The product branching fractions $\mathcal{B}(J/\psi\rightarrow\gamma R, R\ar \gamma \phi)$ are reported, and the resonance parameters of $\eta(1405)$ and $X(1835)$ have been precisely determined. It is more probable that $\eta(1405)$ and $X(1835)$ act as the first - and second - excited states of $\eta^{\prime}$, respectively. The observation of $\eta_{c}\rightarrow\gamma\phi$ holds great significance for the in depth study of charmonium properties. No evidence of $\eta(1295)$, $\eta_{1}(1855)$ or X(2370) is found. The measured upper limits of relevant BF products do not conflict with theoretical expectations for X(2370) as a pseudoscalar glueball and $\eta_{1}(1855)$ as a hybrid state.