What's the difference between a lambda and a neutral sigma particle?

Question

They both have the same quark composition, the same isospin projection, the same charge, etc. The only difference is their mass. The neutral sigma decays very quickly (10^-20 s) into the lambda by EM interaction, but the charged sigmas don't. My question is basically "why is there even a lambda particle at all"? It seems like an island, with no real cause for its existence.

Answer 1

The sigma is an excited state, in which the quarks are not in their ground state orbitals.