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

We study octet-octet baryon (J(P) = 1/2(+)) contact interactions in SU(3) chiral effective field theory by using large-N-c operator analysis. By applying the 1/N-c 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-N-c operator analysis of octet-octet baryon matrix elements reduces the number of free parameters from 15 to 6 at the LO of the 1/N-c expansion. The application of large-N-c sum rules to the Julich 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/N-c 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-N-c analysis than in the heavy baryon (HB) formalism approach. (C) 2019 The Authors. Published by Elsevier B.V.