The baryon has quark content

PHYSICS · Subjective · Fermi University Physics · Quantum Mechanics · Particle Physics & Quantum Fields · Particles, interactions and experiment

Particle Physics, Ch Hadrons: baryons, mesons and their quark content

Problem

The Δ−\Delta^- baryon has quark content dddddd, spin 3/23/2 (all three spins aligned) and measured mass 1232 MeV/c21232\,\mathrm{MeV}/c^2. Someone argues: "The exclusion problem only affects Δ++\Delta^{++}, because that is the one with charge +2+2 that gets discussed. Δ−\Delta^- has charge −1-1, so it needs no extra colour label. Also, adding the three listed quark masses, 3×4.7=14.1 MeV/c23\times 4.7 = 14.1\,\mathrm{MeV}/c^2, comes close enough to explaining the measured 1232 MeV/c21232\,\mathrm{MeV}/c^2 that no further physics is needed. Finally, if I see a decay vertex whose products carry total charge −1-1 and baryon number 11, I can call it a Δ−\Delta^- without reconstructing the invariant mass, since charge and baryon number already match." Identify every error in this argument and give the correct statement in each case.

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