Partial Wave Analysis of $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$

TL;DR

This paper presents a partial wave analysis of $J/ heta$ decays into $\gamma$ and four mesons, identifying several broad resonances and their properties, revealing complex intermediate states in the decay process.

Contribution

It introduces a detailed partial wave analysis of BES data, identifying multiple broad resonances and their characteristics in the decay channel.

Findings

Identification of a broad $0^{-+}$ resonance near 1800 MeV

Observation of a broad $2^{++}$ resonance at 2020 MeV

Evidence for a $2^{-+}$ component at 2.55 GeV

Abstract

BES data on $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $\Gamma = 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ component peaking at 2.55 GeV. The non-$K^*\bar K^*$ contribution is close to phase space; it peaks at 2.6 GeV and is very different from $K^{*}\bar{K^{*}}$.