A baryon comprising uuu (delta++, spin 3/2) exists albeit briefly giving rise to evidence for colour as an additional quantum number, but what's the problem with a uuu particle with spin 1/2? Why can't the individual quarks be RGB, giving a colourless result with the spins being +,+,- to give +1/2 as a total spin? Secondly why can't you have hadrons comprising 4 quarks (colourlessness being retained by having qqbar pairs)? Thirdly, in state vectors, why do some components have positive signs and others negative? Thanks.