Ω−→Ξ−γ andΩ−→Ξ−l+l−decays and the single-quark-transition model

It is shown that the QCD-corrected single-quark transition s→dγ is likely to be the dominant mechanism for ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$γ decay. Various phenomenological implications of this dominance in ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$γ and ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$ $l^{+}$ $l^{\mathrm{-}}$ transitions are presented in detail and compared with predictions of other possible mechanisms. In particular, the single-quark-dominance model gives branching ratios of 1.65×${10}^{\mathrm{-}4}$, 1.4×${10}^{\mathrm{-}6}$, and 6.6×${10}^{\mathrm{-}8}$ for ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$γ, ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$ $e^{+}$ $e^{\mathrm{-}}$, and ${\Omega }^{\mathrm{-}}$→${\Xi }^{\mathrm{-}}$ ${\mu }^{+}$ ${\mu }^{\mathrm{-}}$, respectively. The determination of both the radiative and the Dalitz-pair decays has the potential of revealing the full structure of the flavor-changing sdγ vertex, as well as exploring deviations from the standard model.