Evidence for kappa Meson Production in J/psi -> bar{K}^*(892)^0K^+pi^- Process

TL;DR

This study provides evidence for the kappa meson as an isospinor scalar resonance in J/psi decays, using partial wave analyses of BESII data to determine its mass and width.

Contribution

The paper presents the first evidence of the kappa meson in J/psi decays through detailed partial wave analyses, establishing its resonance parameters.

Findings

Low mass enhancement in K+pi- spectrum observed.

Analysis favors the enhancement being the kappa meson.

Measured mass and width of the kappa meson.

Abstract

Based on 58 million BESII J/psi events, the bar{K}^*(892)^0K^+pi^- channel in K^+K^-pi^+pi^- is studied. A clear low mass enhancement in the invariant mass spectrum of K^+pi^- is observed. The low mass enhancement does not come from background of other J/psi decay channels, nor from phase space. Two independent partial wave analyses have been performed. Both analyses favor that the low mass enhancement is the kappa, an isospinor scalar resonant state. The average mass and width of the kappa in the two analyses are 878 +- 23^{+64}_{-55} MeV/c^2 and 499 +- 52^{+55}_{-87} MeV/c^2, respectively, corresponding to a pole at (841 +- 30^{+81}_{-73}) - i(309 +- 45^{+48}_{-72}) MeV/c^2.