Why isnt there a up,up anti-down baryon?

[Bobhawke]

There doesn't seem to be anything in the theory of the standard model that says such a baryon couldn't exist, so why don't we see it?

 

[Vanadium 50]

There doesn't seem to be anything in the theory of the standard model that says such a baryon couldn't exist

Yes there is. It's colored.

 

[Bobhawke]

ok I feel stupid now.

Im going to go hit myself in the forehead

 

[blechman]

however, you're certainly right that QCD does not forbid many baryonic-like states (such as the pentaquark) that we (debatably) do not see. Why is that? Who knows...