Observation of a broad 1^-- resonant structure around 1.5 GeV/$c^2$ in the K^+K^- mass spectrum in J/psi --> K^+K^-pi^0

TL;DR

This paper reports the discovery of a broad 1^-- resonant structure around 1.5 GeV/c^2 in the K^+K^- mass spectrum from J/psi decays, with parameters inconsistent with known mesons, based on a large data sample.

Contribution

The study provides the first observation and detailed characterization of a new broad 1^-- resonance in J/psi decays, expanding the understanding of meson spectroscopy.

Findings

Observed a broad resonance at 1.5 GeV/c^2 in K^+K^- spectrum.

Determined the resonance's pole position and quantum numbers.

Resonance parameters do not match any known mesons.

Abstract

A broad peak is observed at low K^+K^- invariant mass in J/psi --> K^+K^-pi^0 decays found in a sample of 5.8\times 10^7 J/psi events collected with the BESII detector. A partial wave analysis shows that the J^PC of this structure is 1^--. Its pole position is determined to be (1576^{+49}_{-55}(stat)^{+98}_{-91}(syst)) MeV/c^2 - i(409^{+11}_{-12}$(stat)^{+32}_{-67}(syst)) MeV/c^2. These parameters are not compatible with any known meson resonances.