There are 3 modes of decay via which a $$\Omega ^{-}$$ particle can decay
This is one of the decay:
$$\Omega ^{-} \rightarrow \Xi ^{0} + \pi^{-}$$
Baryon number is conserved. Strangeness number is not conserved so that would imply that the interaction involved is weak Apparently, the rest mass isn't conserved either.
$$\Omega ^{-} = 1672\frac{\rm MeV}{c^{2}}$$ $$\Xi ^{0} = 1315\frac{\rm MeV}{c^{2}}$$ $$\pi^{-} = -140\frac{\rm MeV}{c^{2}}$$
Really, what does this mean? How is this a possible decay mode if the rest mass isn't conserved?