Large-Nc operator analysis of hyperon–nucleon interactions in SU(3) chiral effective field theory

Abstract

We study octet–octet baryon (JP=12+) contact interactions in SU(3) chiral effective field theory by using large-Nc operator analysis. By applying the 1/Nc expansion of the Hartree Hamiltonian, we find 15 operators in the octet–octet baryon potential where 4 operators for the leading order (LO) and 11 for the next-to-next-to-leading order (NNLO). The large-Nc operator analysis of octet–octet baryon matrix elements reduces the number of free parameters from 15 to 6 at the LO of the 1/Nc expansion. The application of large-Nc sum rules to the Jülich model of hyperon–nucleon (YN) interactions at the LO of the chiral expansion reduces the model parameters to 3 from 5 at the LO of 1/Nc expansion. We find that the values of LECs fitted to YN scattering data in Ref. [21] in the relativistic covariant ChEFT (EG) approach are more consistent with the predictions of the large-Nc analysis than in the heavy baryon (HB) formalism approach.