I am trying to figure out the difference between Δ0 and Δ- and the proton and neutron since both appear to have the same combinations of up/down quarks. Deltas have isospin 3/2 and spin angular momentum 3/2 whereas protons and neutrons have isospin 1/2 and spin angular momentum 1/2. I'm thinking that the difference between the two is created via different linear combinations of up and down quarks that meet the isospin and spin angular requirements. For example, Δ0 has the form (neglecting coefficients) of uud + udu + duu and Δ- has the form udd + dud + ddu and both yield isospin = spin = 3/2 Is my thinking correct? I am having a hard time finding a simple description of the quark combinations for the proton and neutronso if anyone has a pointer that would be appreciated. I have been looking at the Wikipedia article on isospin http://en.wikipedia.org/wiki/Isospinon [Broken] but am not sure how to interpret the matrices.