Why are delta-particles so short-lived?

[shelanachium]

When the quark theory was first proposed, it predicted a new baryon, the omega-minus, to complete a set. It is composed of 3 s quarks.

With the nucleons, containing u and d quarks only, the all-d (delta-) and all-u (delta++) exist only as short-lived 'resonances'. Why is this so, when the all-s omega-minus is directly detectible, e.g in bubble-chambers where it was first seen?

 

[Vanadium 50]

It is energetically allowed for Delta++ to go to p pi+. It is energetically forbidden for the Omega- to make the analogous decay, to Cascade0 K-.