Asymmetry in the decay $\Omega^-\to\Xi^-\gamma$

We consider the asymmetry in the decay $\Omega^-\rightarrow\Xi^-\gamma$ assuming that a Vector Meson Dominance approach for the $s\rightarrow d\gamma$ transition gives the dominant contribution. Since in this long-distance approximation the decay is due to a single quark transition $s\rightarrow d\gamma$, the angular distribution asymmetry is given by the single positive asymmetry parameter $\alpha_h = \frac{M^2_s-M^2_d}{M^2_s+M^2_d} = 0.4\pm0.1$. We also discuss the asymmetry in $\Xi \rightarrow \Sigma^-\gamma$, which is expected to be between -0.2 and 0.3.