Observation of $\Omega(2012)^- \to \Xi(1530)\bar{K}$ and measurement of the effective couplings of $\Omega(2012)^-$ to $\Xi(1530)\bar{K}$ and $\Xi\bar{K}$

TL;DR

This paper reports the discovery of a new decay mode of the Omega(2012)^- baryon, measures its mass and effective couplings, and compares decay branching ratios, providing new insights into its properties.

Contribution

The study provides the first observation of the three-body decay of Omega(2012)^-, measuring its mass and effective couplings, advancing understanding of its decay mechanisms.

Findings

Discovery of Omega(2012)^- to Xi(1530) Kbar decay with 5.2 sigma significance.

Measured mass of Omega(2012)^- as 2012.5 MeV with uncertainties.

Determined effective couplings and decay branching ratio, supporting isospin symmetry.

Abstract

Using $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ data collected by the Belle detector, we discover a new three-body decay, $\Omega(2012)^-\to\Xi(1530)\bar K\to\Xi\pi\bar K$, with a significance of 5.2~$\sigma$. The mass of the $\Omega(2012)^-$ is $(2012.5\pm0.7\pm0.5)$ MeV and its effective couplings to $\Xi(1530)\bar{K}$ and $\Xi\bar{K}$ are $(39^{+31}_{-39}\pm9)\times10^{-2}$ and $(1.7\pm0.3\pm0.3)\times10^{-2}$, where the first uncertainties are statistical and the second are systematic. The ratio of the branching fraction for the three-body decay to that for the two-body decay to $\Xi\bar{K}$ is $0.99\pm0.26\pm0.06$, assuming isospin symmetry.