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

Abstract

Abstract Using $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ data collected by the Belle detector, we discover a new resonant three-body decay $\Omega(2012)^-\to \Xi(1530)^0K^-\to\Xi^-\pi^+K^-$ 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 $(41.1\pm35.8\pm6.0)\times10^{-2}$ 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 resonant three-body decay to that for the two-body decay to $\Xi\bar{K}$ is $0.97\pm0.24\pm0.07$ assuming isospin symmetry, consistent with the molecular model of the $\Omega(2012)$, which predicts comparable rates for $\Omega(2012)$ decay to $\Xi(1530)\bar{K}$ and $\Xi\bar{K}$. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.