Excited [70,ℓ+] baryons in large Nc QCD

The masses of the positive parity [70,0+] and [70,2+] non-strange baryons are calculated in large Nc QCD by considering the most dominant operators in an 1/Nc expansion. The approach is based on the introduction of an excited core, obtained after the last particle (an excited quark) has been removed. Configuration mixing is neglected, for simplicity. Although being a sub-leading 1/Nc order, we find that the spin-spin interaction plays a dominant role in describing the data. The role of Nc0 operators is also pointed out. We show how the contribution of the linear term in Nc, of the spin-spin and of the spin-orbit terms vary with the excitation energy.