Partial Wave Analysis of $J/\psi \to \gamma (K^{\pm}K_S^0\pi^{\mp})$

TL;DR

This paper performs a partial wave analysis of $J/$ decays into $ o  K^{\u00b1}K_S^0\u00b7 ext{pi}^{\u00b7}$, identifying resonances and potential hybrid mesons with detailed amplitude fits and mass spectra.

Contribution

It introduces a detailed partial wave analysis of $J/$ radiative decays, revealing new resonance structures and potential hybrid meson candidates.

Findings

Identification of a strong $40$ peak fitted with Breit-Wigner amplitude.

Observation of a second peak at $40$ MeV with a width of about 400 MeV.

Evidence favoring a $0^-$ quantum number for the second peak, suggesting a hybrid meson candidate.

Abstract

BES data on $J/\psi \to \gamma (K^{\pm} K_S^0 \pi^{\mp})$ are presented. There is a strong peak due to $\eta(1440)/\iota$, which is fitted with a Breit-Wigner amplitude with $s$-dependent widths for decays to $K^*K$, $\kappa K$, $\eta \pi\pi$ and $\rho\rho$; $\kappa$ refers to the $K\pi$ S-wave. At a $K\bar{K}\pi$ mass of $\sim 2040$ MeV, there is a second peak with width $\sim 400$ MeV; $J^P = 0^-$ is preferred over $1^+$ and $2^-$ respectively by 5.2 and 6.8 standard deviations. It is a possible candidate for a $0^-$ $s\bar sg$ hybrid partner of $\pi(1800)$.