We study octet–octet baryon (JP=12+) contact interactions in SU(3) chiral effective field theory by using large-Ncoperator analysis. By applying the1/Ncexpansion 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-Ncoperator analysis of octet–octet baryon matrix elements reduces the number of free parameters from 15 to 6 at the LO of the1/Ncexpansion. The application of large-Ncsum 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 of1/Ncexpansion. We find that the values of LECs fitted to YN scattering data in Ref. in the relativistic covariant ChEFT (EG) approach are more consistent with the predictions of the large-Ncanalysis than in the heavy baryon (HB) formalism approach.
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