Three-Quark Currents and Baryon Spin

We show that three-quark axial currents as required by broken SU(6) spin-flavor symmetry reduce the quark spin contribution to proton spin from Σ_p = 1 (one-quark axial current value) to Σ_p = 0.41(12) consistent with the empirical value Σ_p, exp = 0.33(08) . In the case of the Δ^+(1232) baryon, we find that three-quark axial currents increase the one-quark axial current value Σ_Δ^+ = 3 to Σ_Δ^+ = 3.87(22) . We also calculate the quark orbital angular momenta L u and L d in the proton and Δ^+ and interpret our results in terms of the prolate and oblate geometric shapes of these baryons consistent with their intrinsic quadrupole moments.